#include <bits/stdc++.h>
using namespace std;
const int N = 200'000 + 10;
int n, m;
pair<int, int> p[N];
const long long MAX = 1'000'000'000'000'000;
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> m;
for (int i = 1; i <= n; ++i) cin >> p[i].first >> p[i].second;
sort(p + 1, p + n + 1, [](const auto& a, const auto& b) {
return make_pair(a.second, a.first) < make_pair(b.second, b.first);
});
long long answer = -MAX;
for (int i = 1; i <= n; ++i) {
priority_queue<int, vector<int>, greater<>> q;
long long sum = 0;
for (int j = i + 1; j <= n; ++j) {
if ((int)q.size() == m - 2) {
answer = max(answer, p[i].first + 2ll * p[i].second + sum + p[j].first - 2ll * p[j].second);
}
sum += p[j].first;
q.push(p[j].first);
while ((int)q.size() > m - 2) {
sum -= q.top(); q.pop();
}
}
}
cout << answer << "\n";
}
