#include <iostream>
#include <algorithm>
#include <queue>
using namespace std;
#define int long long
#ifdef DEBUG
#define dbg(x) cerr << #x << " = " << x << endl
#define dbgln() cerr << "\n"
#else
#define dbg(x) void(0)
#define dbgln() void(0)
#endif
using PQ = priority_queue<int,vector<int>,greater<int>>;
struct Perle {
int t, c;
bool operator<(const Perle& other) {
return t < other.t;
}
};
int N, M;
vector<Perle> perles;
int ans = -1e18;
void rec(int l, int r, int optl, int optr) {
if (l > r) return;
int mid = (l+r)>>1;
PQ pq;
int sum = 0;
int mini = -1e18;
int opt = N-1;
for (int i = mid; i <= optr; i++) {
if (i >= mid+M) {
sum -= pq.top();
pq.pop();
}
pq.push(perles[i].c);
sum += perles[i].c;
if (i >= mid+M-1) {
int p = sum-2*abs(perles[i].t-perles[mid].t);
if (p > mini) {
opt = i;
mini = p;
}
}
}
ans = max(ans, mini);
rec(l, mid-1, optl, min(opt, optr));
rec(mid+1, r, max(opt, optr), optr);
}
signed main() {
ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
cin >> N >> M;
perles.resize(N);
for (int i = 0; i < N; i++) {
cin >> perles[i].c >> perles[i].t;
}
sort(perles.begin(), perles.end());
rec(0, N-1, M, N-1);
cout << ans << '\n';
}
