#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(x) (x).begin(), (x).end()
const int N = 2e5 + 7;
int n, k;
array<ll, 2> a[N];
int ord[N], pos[N];
ll s[N * 4], t[N * 4];
ll ans = -1e18;
int L = 1, R = 0;
void upd(int i, int x, int v = 1, int l = 1, int r = n) {
if (l == r)
s[v] = x, t[v] = x * a[ord[i]][1];
else {
int m = (l + r) / 2;
if (i <= m)
upd(i, x, v * 2, l, m);
else
upd(i, x, v * 2 + 1, m + 1, r);
s[v] = s[v * 2] + s[v * 2 + 1];
t[v] = t[v * 2] + t[v * 2 + 1];
}
}
ll query(int cnt = 0, int v = 1, int l = 1, int r = n) {
if (l == r) {
return t[v];
}
int m = (l + r) / 2;
if (cnt + s[v * 2] < k - 2)
return t[v * 2] + query(cnt + s[v * 2], v * 2 + 1, m + 1, r);
else
return query(cnt, v * 2, l, m);
}
void shift(int l, int r) {
while (R < r) {
R++;
upd(pos[R], 1);
}
while (L > l) {
L--;
upd(pos[L], 1);
}
while (R > r) {
upd(pos[R], 0);
R--;
}
while (L < l) {
upd(pos[L], 0);
L++;
}
}
void dnq(int l = 1, int r = n - k + 1, int optl = 1, int optr = n) {
if (l > r)
return;
int m = (l + r) / 2;
pair<ll, int> bst = {-1, -1};
for (int i = max(optl, m + k - 1); i <= optr; i++) {
shift(m + 1, i - 1);
bst = max(bst, {query() + a[m][1] + a[i][1] - 2 * (a[i][0] - a[m][0]), i});
}
ans = max(ans, bst.first);
int optm = bst.second;
dnq(l, m - 1, optl, optm);
dnq(m + 1, r, optm, optr);
}
int main() {
cin.tie(0)->sync_with_stdio(false);
cin >> n >> k;
for (int i = 1; i <= n; i++)
cin >> a[i][1] >> a[i][0];
sort(a + 1, a + n + 1);
iota(ord + 1, ord + n + 1, 1);
sort(ord + 1, ord + n + 1, [&](int x, int y) { return a[x][1] > a[y][1]; });
for (int i = 1; i <= n; i++)
pos[ord[i]] = i;
dnq();
cout << ans << '\n';
return 0;
}
