#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int M = 5e6;
const int N = 2e5 + 5;
struct Node {
int lc;
int rc;
ll sum = 0;
int num = 0;
} t[M];
int cnt = 0;
int ti[N];
ll v[N];
ll c[N];
ll ans[N];
ll ord[N];
int n, m;
int modify(int p, int l, int r, int x, int v) {
int u = ++cnt;
if (l == r) {
t[u].sum = t[p].sum + v;
t[u].num = t[p].num + 1;
} else {
int m = (l + r) / 2;
if (x <= m) {
t[u].lc = modify(t[p].lc, l, m, x, v);
t[u].rc = t[p].rc;
} else {
t[u].lc = t[p].lc;
t[u].rc = modify(t[p].rc, m + 1, r, x, v);
}
t[u].sum = t[t[u].lc].sum + t[t[u].rc].sum;
t[u].num = t[t[u].lc].num + t[t[u].rc].num;
}
return u;
}
// make sure it's stuff for l - 1, r
ll query(int num, int pl, int pr, int l, int r) {
// need the highest num in the range [l, r]
if (num == 0)
return 0;
if (l == r) {
return 1LL * ord[l] * num;
}
int mid = (l + r) / 2;
ll rsum = t[t[pr].rc].sum - t[t[pl].rc].sum;
int rnum = t[t[pr].rc].num - t[t[pl].rc].num;
if (rnum >= num)
return query(num, t[pl].rc, t[pr].rc, mid + 1, r);
else
return rsum + query(num - rnum, t[pl].lc, t[pr].lc, l, mid);
}
ll evaluate(int num, int l, int r) {
ll res = query(num , ti[l - 1], ti[r], 1, n);
return res;
}
ll f(int l, int r) {
return evaluate(m, l, r) - 2 * (c[r] - c[l]);
}
void dnc(int l, int r, int gl, int gr) {
if (l > r) return;
int mid = (l + r) / 2;
int best = gl;
for (int i = max(mid + m - 1, gl); i <= gr; i++) {
ll cur = f(mid, i);
assert(i - mid + 1 >= m);
if (cur > ans[mid])
ans[mid] = cur, best = i;
}
dnc(l, mid - 1, gl, best);
dnc(mid + 1, r, best, gr);
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
for (int i = 1; i <= n; i++)
ans[i] = -2e18;
vector<array<ll, 2>> parts(n);
for (int i = 0; i < n; i++)
cin >> parts[i][0] >> parts[i][1];
sort(parts.begin(), parts.end(), [](array<ll, 2> a, array<ll, 2> b) {
return a[1] < b[1];
});
for (int i = 1; i <= n; i++) {
v[i] = parts[i - 1][0];
c[i] = parts[i - 1][1];
}
set<int> vals;
for (int i = 1; i <= n; i++)
vals.insert(v[i]);
map<int, int> conv;
int num = 1;
for (int x : vals)
conv[x] = num, ord[num] = x, num++;
for (int i = 1; i <= n; i++) {
ti[i] = modify(ti[i - 1], 1, n, conv[v[i]], v[i]);
}
dnc(1, n - m + 1, 1, n);
ll res = -2e18 ;
for (int i = 1; i <= n; i++)
res = max(res, ans[i]);
cout << res << '\n';
}
