#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef double db;
typedef string str;
typedef pair<int,int> pi;
typedef pair<ll,ll> pl;
typedef pair<db,db> pd;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<ll> vl;
typedef vector<db> vd;
typedef vector<str> vs;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<pd> vpd;
#define mp make_pair
#define f first
#define s second
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend()
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert
#define ft front()
#define bk back()
#define pf push_front
#define pb push_back
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)
const int MOD = 1e9+7; // 998244353;
const int MX = 2e5+5;
const ll INF = 1e18;
const ld PI = acos((ld)-1);
const int xd[4] = {1,0,-1,0}, yd[4] = {0,1,0,-1};
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count());
template<class T> bool ckmin(T& a, const T& b) {
return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) {
return a < b ? a = b, 1 : 0; }
constexpr int pct(int x) { return __builtin_popcount(x); }
constexpr int bits(int x) { return 31-__builtin_clz(x); } // floor(log2(x))
ll cdiv(ll a, ll b) { return a/b+((a^b)>0&&a%b); } // divide a by b rounded up
ll fdiv(ll a, ll b) { return a/b-((a^b)<0&&a%b); } // divide a by b rounded down
ll half(ll x) { return fdiv(x,2); }
template<class T, class U> T fstTrue(T lo, T hi, U f) {
// note: if (lo+hi)/2 is used instead of half(lo+hi) then this will loop infinitely when lo=hi
hi ++; assert(lo <= hi); // assuming f is increasing
while (lo < hi) { // find first index such that f is true
T mid = half(lo+hi);
f(mid) ? hi = mid : lo = mid+1;
}
return lo;
}
template<class T, class U> T lstTrue(T lo, T hi, U f) {
lo --; assert(lo <= hi); // assuming f is decreasing
while (lo < hi) { // find first index such that f is true
T mid = half(lo+hi+1);
f(mid) ? lo = mid : hi = mid-1;
}
return lo;
}
template<class T> void remDup(vector<T>& v) {
sort(all(v)); v.erase(unique(all(v)),end(v)); }
// INPUT
template<class A> void re(complex<A>& c);
template<class A, class B> void re(pair<A,B>& p);
template<class A> void re(vector<A>& v);
template<class A, size_t SZ> void re(array<A,SZ>& a);
template<class T> void re(T& x) { cin >> x; }
void re(db& d) { str t; re(t); d = stod(t); }
void re(ld& d) { str t; re(t); d = stold(t); }
template<class H, class... T> void re(H& h, T&... t) { re(h); re(t...); }
template<class A> void re(complex<A>& c) { A a,b; re(a,b); c = {a,b}; }
template<class A, class B> void re(pair<A,B>& p) { re(p.f,p.s); }
template<class A> void re(vector<A>& x) { trav(a,x) re(a); }
template<class A, size_t SZ> void re(array<A,SZ>& x) { trav(a,x) re(a); }
// TO_STRING
#define ts to_string
str ts(char c) { return str(1,c); }
str ts(const char* s) { return (str)s; }
str ts(str s) { return s; }
str ts(bool b) {
#ifdef LOCAL
return b ? "true" : "false";
#else
return ts((int)b);
#endif
}
template<class A> str ts(complex<A> c) {
stringstream ss; ss << c; return ss.str(); }
str ts(vector<bool> v) {
str res = "{"; F0R(i,sz(v)) res += char('0'+v[i]);
res += "}"; return res; }
template<size_t SZ> str ts(bitset<SZ> b) {
str res = ""; F0R(i,SZ) res += char('0'+b[i]);
return res; }
template<class A, class B> str ts(pair<A,B> p);
template<class T> str ts(T v) { // containers with begin(), end()
#ifdef LOCAL
bool fst = 1; str res = "{";
for (const auto& x: v) {
if (!fst) res += ", ";
fst = 0; res += ts(x);
}
res += "}"; return res;
#else
bool fst = 1; str res = "";
for (const auto& x: v) {
if (!fst) res += " ";
fst = 0; res += ts(x);
}
return res;
#endif
}
template<class A, class B> str ts(pair<A,B> p) {
#ifdef LOCAL
return "("+ts(p.f)+", "+ts(p.s)+")";
#else
return ts(p.f)+" "+ts(p.s);
#endif
}
// OUTPUT
template<class A> void pr(A x) { cout << ts(x); }
template<class H, class... T> void pr(const H& h, const T&... t) {
pr(h); pr(t...); }
void ps() { pr("\n"); } // print w/ spaces
template<class H, class... T> void ps(const H& h, const T&... t) {
pr(h); if (sizeof...(t)) pr(" "); ps(t...); }
// DEBUG
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) {
cerr << ts(h); if (sizeof...(t)) cerr << ", ";
DBG(t...); }
#ifdef LOCAL // compile with -DLOCAL, chk -> fake assert
#define dbg(...) cerr << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#define chk(...) if (!(__VA_ARGS__)) cerr << "Line(" << __LINE__ << ") -> function(" \
<< __FUNCTION__ << ") -> CHK FAILED: (" << #__VA_ARGS__ << ")" << "\n", exit(0);
#else
#define dbg(...) 0
#define chk(...) 0
#endif
// FILE I/O
void setIn(str s) { freopen(s.c_str(),"r",stdin); }
void setOut(str s) { freopen(s.c_str(),"w",stdout); }
void unsyncIO() { cin.tie(0)->sync_with_stdio(0); }
void setIO(str s = "") {
unsyncIO();
// cin.exceptions(cin.failbit);
// throws exception when do smth illegal
// ex. try to read letter into int
if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
}
typedef pair<ll, int> T;
/**
* Description: 1D range update and query, $SZ=2^p$.
* Source: USACO Counting Haybales
* Verification: SPOJ Horrible
*/
struct LazySeg {
int SZ;
vector<T> sum;
vl vals;
vi to;
LazySeg(vl ats) {
SZ = 1;
while(SZ-1 < sz(ats)-1){
SZ*=2;
}
to = vi(sz(ats), 0);
vector<pair<ll, int>> mto;
for(int i = 0; i < sz(ats); i++){
mto.pb(mp(ats[i], i));
}
sort(all(mto));
for(int i = 0; i < sz(mto); i++){
int ind = mto[i].s;
to[ind] = i;
vals.pb(mto[i].f);
}
sum = vector<T>(2*SZ, mp(ll(0), 0));
for(int i = 0; i < sz(ats); i++){
int ind = to[i];
sum[SZ+ind] = mp(0, 0);
}
}
T comb(T a, T b){
return mp(a.f+b.f, a.s+b.s);
}
// recalc values for current node
void pull(int ind) { sum[ind] = comb(sum[2*ind], sum[2*ind+1]); }
void build() { ROF(i,1,SZ) pull(i); }
void upd(int i, int on, int ind, int L, int R) {
assert(L <= i && i <= R);
if (L == i && R == i) {
if(sum[ind].s != on){
sum[ind].f^=vals[i];
sum[ind].s^=1;
}
assert(sum[ind].s == on);
return;
}
int M = (L+R)/2;
if(i <= M) upd(i, on, 2*ind,L,M);
else upd(i, on, 2*ind+1,M+1,R);
pull(ind);
}
void upd(int ind, int on){ //turning on or off
upd(to[ind], on, 1, 0, SZ-1);
}
ll topk(int k){ //query sum of the top k
if(sum[1].s == k) return sum[1].f;
if(sum[1].s < k) return -INF;
T ans = mp(ll(0), 0);
int ind = 1;
while(2*ind+1 < 2*SZ){
if(comb(ans, sum[2*ind+1]).s <= k){
ans = comb(ans, sum[2*ind+1]);
ind = 2*ind;
}
else{
ind = 2*ind+1;
}
}
return ans.f;
}
};
const int mx = 200005;
pl CV[mx];
int N, M;
ll ans = -INF;
LazySeg lseg({});
void solve(int l, int r, int L, int R){ //[1, l-1] = 0, [l, L-1] = 1, [L, R] = 0, [R+1, N] = 0
if(l > r) return;
// dbg(l, r, L, R);
// for(int i = 1; i <= N; i++){
// dbg(i, lseg.sum[i+lseg.SZ], lseg.vals[i]);
// }
// if(l == 4 && r == 6 && L == 7 && R == 8){
// for(int i = 1; i <= N; i++){
// dbg(i, lseg.sum[i+lseg.SZ], lseg.vals[i]);
// }
// }
ckmax(L, l);
//assert(L >= l);
int m = (l+r)/2;
int ind = -1;
ll cans = -INF;
for(int i = l; i <= m; i++){
lseg.upd(i, 0);
}
for(int i = max(m+1, L); i <= R; i++){
ll pans = lseg.topk(M-2)+CV[i].s+CV[m].s-2*(CV[i].f-CV[m].f);
if(pans > cans){
cans = pans;
ind = i;
}
lseg.upd(i, 1);
}
//dbg(l, r, L, R, m, ind);
ckmax(ans, cans);
for(int i = l; i <= min(L-1, m); i++){
lseg.upd(i, 1);
}
for(int i = max(m+1, L); i <= R; i++){
lseg.upd(i, 0);
}
// if(l == 4 && r == 6 && L == 7 && R == 8){
// for(int i = 1; i <= N; i++){
// dbg(i, lseg.sum[i+lseg.SZ], lseg.vals[i]);
// }
// }
solve(l, m-1, L, ind);
for(int i = l; i <= m; i++){
lseg.upd(i, 0);
}
for(int i = max(m+1, L); i <= ind-1; i++){
lseg.upd(i, 1);
}
solve(m+1, r, ind, R);
for(int i = max(m+1, L); i <= ind-1; i++){
lseg.upd(i, 0);
}
for(int i = l; i <= min(L-1, m); i++){
lseg.upd(i, 1);
}
}
int main() {
setIO();
cin >> N >> M;
for(int i = 1; i <= N; i++){
cin >> CV[i].s >> CV[i].f;
}
sort(CV+1, CV+1+N);
vl vals;
vals.pb(0);
for(int i = 1; i <= N; i++){
vals.pb(CV[i].s);
}
lseg = LazySeg({vals});
solve(1, N-M+1, 1, N);
ps(ans);
// you should actually read the stuff at the bottom
}
/* stuff you should look for
* int overflow, array bounds
* special cases (n=1?)
* do smth instead of nothing and stay organized
* WRITE STUFF DOWN
*/
