#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
const int N = 2e5 + 7;
const ll Inf = 5e18;
struct Node {
ll sum;
int cnt, L, R;
Node(int val) {
sum = val;
cnt = 1;
L = R = -1;
}
Node(ll sum, int cnt) : sum(sum), cnt(cnt), L(-1), R(-1) {}
Node(ll sum, int cnt, int L, int R) : sum(sum), cnt(cnt), L(L), R(R) {}
Node() : sum(0), cnt(0), L(-1), R(-1) {}
};
vector <Node> t;
int build(int l, int r) {
if (l == r) {
t.push_back(Node());
return (int)t.size() - 1;
} else {
int m = (l + r) >> 1;
int L = build(l, m);
int R = build(m + 1, r);
t.push_back(Node(0, 0, L, R));
return (int)t.size() - 1;
}
}
ll val[N];
int modify(int id, int v, int l, int r) {
if (l == r) {
t.push_back(Node(t[v].sum + val[id], t[v].cnt + 1));
return (int)t.size() - 1;
} else {
int m = (l + r) >> 1;
if (id <= m) {
int L = modify(id, t[v].L, l, m);
int R = t[v].R;
t.push_back(Node(t[L].sum + t[R].sum, t[L].cnt + t[R].cnt, L, R));
return (int)t.size() - 1;
} else {
int L = t[v].L;
int R = modify(id, t[v].R, m + 1, r);
t.push_back(Node(t[L].sum + t[R].sum, t[L].cnt + t[R].cnt, L, R));
return (int)t.size() - 1;
}
}
}
ll get(int k, int vl, int vr, int l, int r) {
if (l == r) {
return (ll)k * val[l];
} else {
int m = (l + r) >> 1;
if (t[t[vr].R].cnt - t[t[vl].R].cnt >= k) {
return get(k, t[vl].R, t[vr].R, m + 1, r);
} else {
return t[t[vr].R].sum - t[t[vl].R].sum + get(k - (t[t[vr].R].cnt - t[t[vl].R].cnt), t[vl].L, t[vr].L, l, m);
}
}
}
vector <int> roots;
int sz, n, m;
ll ans = -5e18;
vector <pair <int, int>> a;
ll get(int l, int r) {
return get(m, roots[l], roots[r + 1], 0, sz - 1) - 2 * a[r].first + 2 * a[l].first;
}
void rec(int l, int r, int opt_l, int opt_r) {
if (l > r) return;
int mid = (l + r) >> 1;
int opt_m = opt_r;
ll res = -5e18;
for (int i = max(mid + m - 1, opt_l); i <= opt_r; ++i) {
ll cur = get(mid, i);
ans = max(ans, cur);
if (cur > res) {
res = cur;
opt_m = i;
}
}
rec(l, mid - 1, opt_l, opt_m);
rec(mid + 1, r, opt_m, opt_l);
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.setf(ios::fixed); cout.precision(20);
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
cin >> n >> m;
a.resize(n);
for (int i = 0; i < n; ++i) cin >> a[i].second >> a[i].first;
sort(a.begin(), a.end());
vector <int> cm;
for (int i = 0; i < n; ++i) cm.push_back(a[i].second);
sort(cm.begin(), cm.end());
cm.resize(unique(cm.begin(), cm.end()) - cm.begin());
sz = cm.size();
roots.push_back(build(0, sz - 1));
for (int i = 0; i < (int)cm.size(); ++i) val[i] = cm[i];
for (int i = 0; i < n; ++i) {
int id = lower_bound(cm.begin(), cm.end(), a[i].second) - cm.begin();
roots.push_back(modify(id, roots.back(), 0, sz - 1));
}
rec(0, n - 1, 0, n - 1);
cout << ans << '\n';
}
