#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
#define f first
#define s second
#define endl "\n"
const int N = 2e5 + 5, mod = 1e9 + 7; //!
int t, n, ans = 0;
pii p[N];
int m;
int get(int sum, multiset<int> s, int a, int b) {
int x = m;
if(s.count(a) == 0) x--, sum += a;
if(s.count(b) == (a == b)) x--, sum += b;
while(s.size() > x) {
sum -= *s.begin();
s.erase(s.find(*s.begin()));
}
return sum;
}
void solve(int l,int r,int ql, int qr) {
if(r < l) return;
int mid = (l + r) >> 1, sum = 0;
pii opt; opt = {-2e9, 0};
multiset<int> s;
for(int i = mid; i >= ql; i--) {
s.insert(p[i].s); sum += p[i].s;
if(s.size() == m + 1) {
sum -= *s.begin();
s.erase(s.find(*s.begin()));
}
if(mid - i + 1 >= m) {
opt = max(opt, {get(sum, s, p[i].s, p[mid].s) - 2 * (p[mid].f - p[i].f), i});
}
}
ans = max(ans, opt.f);
if(l == r) return;
solve(l, mid - 1, ql, opt.s); solve(mid + 1,r, opt.s, qr);
}
main() {
ios_base::sync_with_stdio(false),
cin.tie(0),cout.tie(0);
cin >> n >> m;
for(int i = 1; i <= n; i++) {
cin >> p[i].s >> p[i].f;
}
sort(p + 1, p + n + 1);
solve(m, n, 1, n - m + 1);
cout << ans;
}
