#include <bits/stdc++.h>
using namespace std;
#define int long long
bool cmp(pair<int,int> a, pair<int,int> b) {
if (a.second != b.second) return a.second < b.second;
return a.first < b.first;
}
const int maxn = 2e5 + 5, INF = 1e18;
int n, m;
pair<int,int> a[maxn];
int ans = -INF;
void cal(vector<pair<int,int>> vec) {
sort(vec.begin(), vec.end(), cmp);
int sz = vec.size();
// cout << sz << endl;
for (int i=1;i<sz;i++) vec[i].first += vec[i-1].first;
for (int r = m-1; r < sz; r++) {
int l = r - m + 1;
int curans = vec[r].first;
if (l > 0) curans -= vec[l-1].first;
curans -= (vec[r].second - vec[l].second) * 2;
// cout << sz << " " << r << " " << curans << endl;
ans = max(curans, ans);
}
}
signed main() {
ios::sync_with_stdio(0); cin.tie(0);
cin >> n >> m;
for (int i=1;i<=n;i++) cin >> a[i].first >> a[i].second;
sort(a+1, a+n+1);
reverse(a+1, a+n+1);
vector<pair<int,int>> vec;
for (int i=1;i<=n;i++) {
vec.push_back(a[i]);
if (i >= m) cal(vec);
}
cout << ans << "\n";
}
