#include<bits/stdc++.h>
using namespace std;
struct Lisan: vector<int> {
void done() { sort(begin(), end()); erase(unique(begin(), end()), end()); }
const int operator () (const int& v) const { return lower_bound(begin(), end(), v) - begin(); }
};
struct DS {
int N, M, lp, rp;
vector<int> val;
Lisan lisan;
vector<int64_t> sum;
vector<int> cnt;
DS (int _M): M(_M), val(1, 0) {}
void add(const int& v) { lisan.emplace_back(v); val.emplace_back(v); }
void build() {
lisan.done();
N = lisan.size();
lp = 1; rp = 0;
sum.assign(N * 4, 0ll);
cnt.assign(N * 4, 0);
}
void modify(int i, int l, int r, int p, int v) {
if (l + 1 == r) {
sum[i] += lisan[p] * v;
cnt[i] += v;
return;
}
int m = (l + r) / 2;
if (p < m) modify(i * 2, l, m, p, v);
else modify(i * 2 + 1, m, r, p, v);
sum[i] = sum[i * 2] + sum[i * 2 + 1];
cnt[i] = cnt[i * 2] + cnt[i * 2 + 1];
return;
}
int64_t query(int i, int l, int r, int k) {
if (l + 1 == r)
return (int64_t) lisan[l] * k;
if (cnt[i] == k)
return sum[i];
int m = (l + r) / 2;
if (cnt[i * 2 + 1] >= k)
return query(i * 2 + 1, m, r, k);
return sum[i * 2 + 1] + query(i * 2, l, m, k - cnt[i * 2 + 1]);
}
void clean() {
for (int i = lp; i <= rp; ++i)
modify(1, 0, N, lisan(val[i]), -1);
lp = 1; rp = 0;
}
int64_t query(int l, int r) {
if (l < lp) clean();
while (rp < r) modify(1, 0, N, lisan(val[++rp]), 1);
while (lp < l) modify(1, 0, N, lisan(val[lp++]), -1);
return query(1, 0, N, M);
}
};
int main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int N, M; cin >> N >> M;
vector<pair<int, int>> cakes(N + 1);
for (int i = 1; i <= N; ++i)
cin >> cakes[i].second >> cakes[i].first;
sort(begin(cakes) + 1, end(cakes));
DS ds(M);
for (int i = 1; i <= N; ++i)
ds.add(cakes[i].second);
ds.build();
int64_t ans = LLONG_MIN;
queue<tuple<int, int, int, int>> q;
q.emplace(1, N - M + 1, M, N);
while (!q.empty()) {
auto [l, r, sl, sr] = q.front(); q.pop();
r = min(r, sr - M + 1);
if (l > r) continue;
int m = (l + r) / 2;
int bests = -1;
int64_t bestv = LLONG_MIN;
for (int i = max(sl, m + M - 1); i <= sr; ++i) {
int64_t val = ds.query(m, i) - 2ll * (cakes[i].first - cakes[m].first);
if (val > bestv) {
bests = i;
bestv = val;
}
}
ans = max(ans, bestv);
if (l <= m - 1) q.emplace(l, m - 1, sl, bests);
if (m + 1 <= r) q.emplace(m + 1, r, bests, sr);
}
cout << ans << '\n';
return 0;
}
