#include <bits/stdc++.h>
#define debug(x) [&](){ auto _x = x; cerr << __LINE__ << ": " << #x << " = " << _x << endl; }()
using namespace std;
typedef long long ll;
#define int ll
typedef pair<int, int> pint;
#define all(x) x.begin(), x.end()
const int INF = 1e9, LLINF = 1e18;
int n, m, v[200001], c[200001], ans;
struct Node {
int l, r, freq = 0, sum = 0;
Node *lc = nullptr, *rc = nullptr;
Node *update(int i) {
auto ret = new Node{l, r, freq, sum, lc, rc};
if (l == r) ret->freq++, ret->sum += l;
else {
int m = (l + r) >> 1;
if (i <= m) ret->lc = (ret->lc ? ret->lc : new Node{l, m})->update(i);
else ret->rc = (ret->rc ? ret->rc : new Node{m + 1, r})->update(i);
ret->freq = (ret->lc ? ret->lc->freq : 0) + (ret->rc ? ret->rc->freq : 0);
ret->sum = (ret->lc ? ret->lc->sum : 0) + (ret->rc ? ret->rc->sum : 0);
}
return ret;
}
} *st[200001];
int walk(Node *l, Node *r, int k) {
if (r->l == r->r) return k * r->l;
int rfreq = r->rc ? r->rc->freq - (l and l->rc ? l->rc->freq : 0) : 0;
if (k <= rfreq) return walk(l ? l->rc : nullptr, r->rc, k);
else return walk(l ? l->lc : nullptr, r->lc, k - rfreq) + (r->rc ? r->rc->sum - (l and l->rc ? l->rc->sum : 0) : 0);
}
int calc(int l, int r) {
if (r - l + 1 < m) return -LLINF;
return walk(st[l - 1], st[r], m) - (c[r] - c[l]) * 2;
}
void dnc(int l, int r, int optl, int optr) {
if (l > r) return;
int mid = (l + r) >> 1;
pint mx{-LLINF, 0};
for (int k = max(optl, mid + m - 1); k <= optr; ++k) {
mx = max(mx, {calc(mid, k), k});
}
ans = max(ans, mx.first);
dnc(l, mid - 1, optl, mx.second);
dnc(mid + 1, r, mx.second, optr);
}
int32_t main() {
cin >> n >> m;
vector<pint> raw(n);
for (auto &[b, a]: raw) cin >> a >> b;
sort(all(raw));
st[0] = new Node{1, INF};
for (int i = 1; i <= n; ++i) {
tie(c[i], v[i]) = raw[i - 1];
st[i] = st[i - 1]->update(v[i]);
}
ans = -LLINF;
dnc(1, n - m + 1, m, n);
cout << ans << endl;
}
