#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define sz(a) ((int) a.size())
#define F first
#define S second
const int N = 3e5 + 15;
int n, K;
pair<int, int> a[N];
ll ans = -1e18;
int L = 1, R = 0;
ll cur = 0;
set<pair<int, int>> sm, bg;
void add(int p) {
if(sz(bg) < K) {
cur += a[p].S;
bg.insert({a[p].S, p});
} else {
assert(sz(bg) == K);
if(a[p].S > (*(bg.begin())).F) {
cur -= (*bg.begin()).F;
sm.insert(*bg.begin());
bg.erase(bg.begin());
bg.insert({a[p].S, p});
cur += a[p].S;
} else {
sm.insert({a[p].S, p});
}
}
}
void del(int p) {
if(bg.count({a[p].S, p})) {
cur -= a[p].S;
bg.erase({a[p].S, p});
if(sz(sm)) {
auto it = sm.end();
it--;
cur += (*it).F;
bg.insert(*it);
sm.erase(it);
}
} else {
assert(sm.find({a[p].S, p}) != sm.end());
sm.erase(sm.find({a[p].S, p}));
}
}
void dnc(int l, int r, int tl, int tr) {
if(l > r) {
return;
}
int m = (l + r) / 2;
int pt = tl;
ll mx = -1e18;
//cout << l << ' ' << r << ' ' << tl << ' ' << tr << '\n';
for(int k = max(m, tl); k <= tr; k++) {
while(R < k) {
add(++R);
}
while(L > m) {
add(--L);
}
while(R > k) {
del(R--);
}
while(L < m) {
del(L++);
}
if(sz(bg) == K && mx < cur - 2 * (a[k].F - a[m].F)) {
mx = cur - 2 * (a[k].F - a[m].F);
pt = k;
}
}
ans = max(ans, mx);
dnc(l, m - 1, tl, pt);
dnc(m + 1, r, pt, tr);
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> K;
for(int i = 1; i <= n; i++) {
cin >> a[i].S;
cin >> a[i].F;
}
sort(a + 1, a + n + 1);
dnc(1, n, 1, n);
cout << ans << '\n';
}
