#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int MAXN = 2e5 + 5;
ll N, M, ans;
pii A[MAXN];
ll comp[MAXN], root[MAXN];
int get_idx(ll val) { return lower_bound(comp+1, comp+1+N, val) - comp; }
struct PST {
struct NODE { ll l, r, cnt, sum; } T[MAXN * 30];
int sz;
int make(int v, int l, int r, int n) {
if(r < v || v < l) return n;
int cur = ++sz;
T[cur] = T[n];
if(l != r) {
int mid = l + r >> 1;
T[cur].l = make(v, l, mid, T[n].l);
T[cur].r = make(v, mid+1, r, T[n].r);
}
T[cur].cnt++;
T[cur].sum += comp[v];
return cur;
}
ll query(int tot, int l, int r, int n1, int n2) {
if(l == r) {
int cnt = M - tot;
return comp[l] * cnt;
}
int cnt = T[T[n2].r].cnt - T[T[n1].r].cnt;
ll sum = T[T[n2].r].sum - T[T[n1].r].sum;
int mid = l + r >> 1;
if(tot + cnt >= M) return query(tot, mid+1, r, T[n1].r, T[n2].r);
else return sum + query(tot + cnt, l, mid, T[n1].l, T[n2].l);
}
} pst;
void f(int s, int e, int l, int r) {
if(l > r) return;
if(e < l) assert(0);
int mid = l + r >> 1;
ll k, MAX = -1e18;
for(int i=max(s, mid); i<=e; i++) {
ll q = pst.query(0, 1, N, root[mid-1], root[i]) - 2 * (A[i].fi - A[mid].fi);
if(MAX < q) {
MAX = q;
k = i;
}
}
ans = max(ans, MAX);
f(s, k, l, mid-1); f(k, e, mid+1, r);
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
cin >> N >> M;
for(int i=1; i<=N; i++) {
cin >> A[i].se >> A[i].fi;
comp[i] = A[i].se;
}
sort(comp+1, comp+1+N);
sort(A+1, A+1+N);
for(int i=1; i<=N; i++) root[i] = pst.make(get_idx(A[i].se), 1, N, root[i-1]);
f(1, N, 1, N);
cout << ans;
}
