#include <bits/stdc++.h>
#define IO_OP std::ios::sync_with_stdio(0); std::cin.tie(0);
#define F first
#define S second
#define V vector
#define PB push_back
#define MP make_pair
#define EB emplace_back
#define ALL(v) (v).begin(), (v).end()
using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
typedef V<int> vi;
void DBG() { cerr << "]" << endl; }
template<class H, class...T> void DBG(H h, T ...t) {
cerr << to_string(h);
if(sizeof ...(t)) cerr << ", ";
DBG(t...);
}
#define debug(...) cerr << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
const int INF = 1e9 + 7, N = 2e5 + 7;
const ll oo = 1e18 + 7;
vi compress;
struct node {
node *l, *r;
ll sum, cnt;
node() {
l = r = nullptr;
sum = cnt = 0;
}
node(node* _l, node* _r) {
l = _l, r = _r;
sum = (l ? l -> sum : 0LL) + (r ? r -> sum : 0LL);
cnt = (l ? l -> cnt : 0LL) + (r ? r -> cnt : 0LL);
}
};
ll cnt(node* t) {
return t ? t -> cnt : 0LL;
}
ll sum(node* t) {
return t ? t -> sum : 0LL;
}
node* lc(node* t) {
return t ? t -> l : nullptr;
}
node* rc(node* t) {
return t ? t -> r : nullptr;
}
node* h[N];
node* add(node* t, int pos, int tl = 0, int tr = compress.size()) {
if(tr - tl == 1) {
node* tt = new node();
tt -> sum = sum(t) + compress[pos];
tt -> cnt = cnt(t) + 1;
return tt;
}
int tm = (tl + tr) / 2;
if(pos < tm)
return new node(add(lc(t), pos, tl, tm), rc(t));
else
return new node(lc(t), add(rc(t), pos, tm, tr));
}
ll qry(node* t1, node* t2, int m, int tl = 0, int tr = compress.size()) {
if(cnt(t2) - cnt(t1) == m)
return sum(t2) - sum(t1);
if(tr - tl == 1)
return 1LL * compress[tl] * m;
int tm = (tl + tr) / 2;
if(cnt(rc(t2)) - cnt(rc(t1)) >= m)
return qry(rc(t1), rc(t2), m, tm, tr);
else {
int x = cnt(rc(t2)) - cnt(rc(t1));
return sum(rc(t2)) - sum(rc(t1)) + qry(lc(t1), lc(t2), m - x, tl, tm);
}
}
ll qry(int l, int r, int m) {
assert(r - l >= m);
return qry(h[l], h[r], m);
}
signed main() {
IO_OP;
int n, m;
cin >> n >> m;
m -= 2;
V<pi> a(n); // c, v
for(int i = 0; i < n; i++) {
cin >> a[i].S >> a[i].F;
compress.PB(a[i].S);
}
sort(ALL(a));
sort(ALL(compress));
compress.resize(unique(ALL(compress)) - compress.begin());
h[0] = nullptr;
for(int i = 1; i <= n; i++) {
int tt = lower_bound(ALL(compress), a[i - 1].S) - compress.begin();
h[i] = add(h[i - 1], tt);
// debug(h[i] -> cnt);
}
auto cost = [&] (int j, int i) {
if(i - j - 1 < m) return -oo;
return 0LL + 2 * a[j].F - 2 * a[i].F + a[i].S + a[j].S + qry(j + 1, i, m);
};
ll ans = -oo;
function<void(int, int, int, int)> solve = [&] (int l, int r, int ql, int qr) {
if(l > r)
return;
if(r == l) {
for(int i = ql; i <= qr; i++)
ans = max(ans, cost(i, l));
return;
}
int m = (l + r) / 2;
ll mx = -oo, qm = -1;
for(int i = ql; i <= qr; i++) {
ll tt = cost(i, m);
if(tt > mx) {
mx = tt;
qm = i;
}
}
assert(qm != -1);
ans = max(ans, mx);
solve(l, m - 1, ql, qm);
solve(m + 1, r, qm, qr);
};
solve(m + 1, n - 1, 0, n - 1);
cout << ans << '\n';
}
