#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#define D(x...) printf(x)
#else
#define D(x...)
#endif
#define MN 200100
#define x first
#define y second
using ll = long long;
ll N, M, pos[MN], ans = -1e17;
pair<ll, ll> A[MN], ord[MN];
pair<ll, ll> t[4*MN]; // (cnt, sum)
struct State {
ll l, h; // where the endpoint can be [l, h)
ll ansl, ansh; // where the optimal point can be [ansl, ansh)
};
vector<State> level[20];
void update(ll n, ll a, ll b, ll x, ll v) {
if (a == b-1) {
if (v > 0) t[n].x++;
else t[n].x--;
t[n].y += v;
} else {
int m = (a+b)/2;
if (x < m) update(2*n, a, m, x, v);
else update(2*n+1, m, b, x, v);
t[n].x = t[2*n].x+t[2*n+1].x;
t[n].y = t[2*n].y+t[2*n+1].y;
}
}
ll query(ll n, ll a, ll b, ll x) {
if (a == b-1) return t[n].y;
int m = (a+b)/2;
if (t[2*n].x >= x) return query(2*n, a, m, x);
return t[2*n].y+query(2*n+1, m, b, x-t[2*n].x);
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> N >> M;
for (int i = 0; i < N; i++) cin >> A[i].y >> A[i].x;
sort(A, A+N); reverse(A, A+N);
for (int i = 0; i < N; i++) ord[i] = {A[i].y, i};
sort(ord, ord+N); reverse(ord, ord+N);
for (int i = 0; i < N; i++) pos[ord[i].y] = i;
level[0].push_back({0, N, 0, N});
for (int i = 0; level[i].size(); i++) {
D("LEVEL %d ===================\n", i);
int curl = 0, curr = 0;
for (State j : level[i]) {
D("state = %lld %lld %lld %lld\n", j.l, j.h, j.ansl, j.ansh);
int m = (j.l+j.h)/2;
assert(curr <= m);
while (curr <= m) {
D("push in %d %d %d\n", curr, pos[curr], A[curr].y);
update(1, 0, N, pos[curr], A[curr].y);
curr++;
}
assert(curl <= j.ansl);
while (curl < j.ansl) {
D("pop out %d %d %d\n", curl, pos[curl], -A[curl].y);
update(1, 0, N, pos[curl], -A[curl].y);
curl++;
assert(curl <= curr);
}
ll curbest = -1e17, curpos = -1;
assert(curl < j.ansh);
while (curr-curl >= M) {
ll cur = query(1, 0, N, M)-2*A[curl].x;
D("try %d %d\n", curl, cur);
if (cur > curbest) {
curbest = cur;
curpos = curl;
}
if (curl == j.ansh-1) break;
update(1, 0, N, pos[curl], -A[curl].y);
curl++;
}
D("curl = %d curr = %d\n", curl, curr);
if (curpos != -1) {
if (j.l < j.h-1) {
level[i+1].push_back({j.l, m, j.ansl, curpos+1});
level[i+1].push_back({m, j.h, curpos, j.ansh});
}
ans = max(ans, curbest+2*A[m].x);
}
D("hello\n");
}
while (curl < curr) {
update(1, 0, N, pos[curl], -A[curl].y);
curl++;
}
}
cout << ans << "\n";
}
