#include <bits/stdc++.h>
#define f first
#define s second
using namespace std;
typedef long long ll;
const int N = 1e5+5;
ll n, k, ans;
pair<int, int> p[N];
bool cmp(pair<int, int> a, pair<int, int> b)
{
return a.s < b.s;
}
ll sum(int l, int r)
{
vector<ll> vec;
ll ret = 0;
for(int i=l; i<=r; i++)
{
vec.push_back(p[i].f);
}
sort(vec.rbegin(), vec.rend());
for(int i=0; i<min(k, (ll)vec.size()); i++) ret += vec[i];
return ret;
}
void solve(int l, int r, int s, int e)
{
if(l > r) return ;
ll id = -1, m = -1;
int mid = (l+r)>>1;
for(int i=max(mid+k-1, (ll)s); i<e; i++)
{
if(sum(mid, i) - (p[i].s-p[mid].s)*2 > m)
m = sum(mid, i) - (p[i].s-p[mid].s)*2, id = i;
}
solve(l, mid-1, s, id+1);
solve(mid+1, r, id, e);
ans = max(ans, m);
}
int main()
{
cin >> n >> k;
for(int i=0; i<n; i++) cin >> p[i].f >> p[i].s;
sort(p, p+n, cmp);
solve(0, n, 0, n);
cout << ans << endl;
}
