#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define int ll
#define pii pair<int, int>
#define ull unsigned ll
#define f first
#define s second
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
#define SQ(x) (x)*(x)
#define MN(a,b) a = min(a,(__typeof__(a))(b))
#define MX(a,b) a = max(a,(__typeof__(a))(b))
#define pb push_back
#define REP(i,n) for (int i = 0; i<n; ++i)
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#ifdef BALBIT
#define IOS()
#define bug(...) fprintf(stderr,"#%d (%s) = ",__LINE__,#__VA_ARGS__),_do(__VA_ARGS__);
template<typename T> void _do(T &&x){cerr<<x<<endl;}
template<typename T, typename ...S> void _do(T &&x, S &&...y){cerr<<x<<", ";_do(y...);}
#else
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0);
#define endl '\n'
#define bug(...)
#endif
const int iinf = 1e9+10;
const ll inf = 1ll<<60;
const ll mod = 1e9+7 ;
void GG(){cout<<"0\n"; exit(0);}
ll mpow(ll a, ll n, ll mo = mod){ // a^n % mod
ll re=1;
while (n>0){
if (n&1) re = re*a %mo;
a = a*a %mo;
n>>=1;
}
return re;
}
ll inv (ll b, ll mo = mod){
if (b==1) return b;
return (mo-mo/b) * inv(mo%b,mo) % mo;
}
const int maxn = 2e5+5;
int n, M;
multiset<int> top; // the top <=M best cakess
multiset<int> backup; // remaining cakes
ll now = 0; // sum of cakes in top
int rL = 0, rR = -1; // range, inclusive
int val[maxn];
ll pos[maxn];
void AAA(bool t) {
if (!t) {
cout<<"death"<<endl;
exit(0);
}
}
void add(int p) {
AAA(p>=0);
now += val[p];
top.insert(val[p]);
if (SZ(top) > M) {
now -= *top.begin();
backup.insert(*top.begin());
top.erase(top.find(*top.begin()));
}
}
void del(int p) {
AAA(p>=0);
if (SZ(backup) && (*backup.rbegin() >= val[p])){
// remove from backup
backup.erase(backup.find(val[p]));
}else{
AAA(SZ(top));
now -= val[p];
top.erase(top.find(val[p]));
}
}
inline ll gat() {
if (SZ(top) < M) return -inf+10;
return now - 2*(pos[rR] - pos[rL]);
}
ll re = -inf;
void DandC(int l, int r, int ql, int qr) {
if (l > r) return;
int mid = (l+r)/2;
while (rL > ql) {
add(--rL);
}
while (rR < mid) {
add(++rR);
}
while (rL < ql) {
del(rL++);
}
while (rR > mid) {
del(rR--);
}
ll bst = -inf;
int bat = -1;
AAA(rL == ql && rR == mid);
for (int ty = ql; ty <= min(qr, mid); ++ty) {
// AAA(rR == mid && rL == ty);
if (gat() > bst) {
bst = gat(); bat = ty;
}
if (ty != min(qr,mid)) {
del(rL++);
}
}
AAA(bat != -1);
bug(mid, bat, bst);
MX(re, bst);
DandC(l,mid-1,ql, bat);
DandC(mid+1,r,bat,qr);
}
signed main(){
IOS();
cin>>n>>M;
vector<pii> hey;
REP(i,n) {
int a,b; cin>>a>>b;
hey.pb({b,a});
}
sort(ALL(hey));
REP(i,n) {
pos[i] = hey[i].f;
val[i] = hey[i].s;
}
// return 0;
DandC(M-1,n-1,0,n-1);
cout<<re<<endl;
}
