#include <iostream>
#include <set>
#include <algorithm>
#include <utility>
using namespace std;
using ll = long long;
const ll inf = 1e18;
pair<ll, int> arr[200005];
int N, M;
int l, r;
set<pair<ll, int>> inc, exc;
ll cur = 0;
void in(int i)
{
inc.insert(make_pair(arr[i].first, i));
cur += arr[i].first;
cur -= (*inc.begin()).first;
exc.insert(*inc.begin());
inc.erase(inc.begin());
}
void out(int i)
{
auto it = inc.find(make_pair(arr[i].first, i));
if (it != inc.end()) {
cur -= arr[i].first;
inc.erase(it);
cur += (*--exc.end()).first;
inc.insert(*--exc.end());
exc.erase(--exc.end());
}
else {
exc.erase(make_pair(arr[i].first, i));
}
}
void put(int ln, int rn)
{
while (l-- > ln) in(l);
while (r++ < rn) in(r);
while (l < ln) out(l++);
while (r > rn) out(r--);
}
ll res[200005];
void dnc(int s, int e, int l, int r)
{
if (s > e) return;
int m = s + e >> 1;
int ml = max(m + M - 1, l), mr = r;
if (ml > mr) {
dnc(s, m - 1, l, r);
}
else {
int pv = -1;
for (int i = ml; i <= mr; i++) {
put(m, i);
ll tmp = cur - 2 * (arr[i].second - arr[m].second);
if (res[m] < tmp) {
res[m] = tmp;
pv = i;
}
}
dnc(s, m - 1, l, pv);
dnc(m + 1, e, pv, r);
}
}
int main()
{
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> N >> M;
for (int i = 1; i <= N; i++) {
cin >> arr[i].first >> arr[i].second;
}
fill(res + 1, res + N + 1, -inf);
sort(arr + 1, arr + N + 1, [&](auto &p1, auto &p2){return p1.second < p2.second;});
l = 1, r = M;
for (int i = 1; i <= M; i++) {
inc.insert(make_pair(arr[i].first, i));
cur += arr[i].first;
}
dnc(1, N-M+1, M, N);
ll ans = *max_element(res + 1, res + N + 1);
cout << ans << '\n';
}
