// vaziat meshki-ghermeze !
#include <bits/stdc++.h>
#define pb push_back
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " : " << x << '\n'
using namespace std;
typedef long long ll;
typedef long double ld;
typedef string str;
typedef pair<ll, ll> pll;
const ll Mod = 1000000007LL;
const int N = 2e5 + 10;
const ll Inf = 2242545357980376863LL;
const ll Log = 30;
vector<pll> A, V;
ll ans = -Inf;
int ridx[N];
int n, m;
struct Fenwick {
ll fen[N];
Fenwick (){
memset(fen, 0, sizeof fen);
}
void Add(int idx, ll x){
// cerr << "^^ " << idx << ' ' << x << '\n';
idx += 2;
for(; idx < N; idx += (idx & (-idx)))
fen[idx] += x;
}
ll Get(int idx){
idx += 2;
ll res = 0;
for(; idx; idx -= (idx & (-idx)))
res += fen[idx];
return res;
}
ll GetK(int k){
int nw = 0;
for(int i = Log - 1; i >= 0; i--){
int st = (1 << i);
if(nw + st >= N) continue;
if(fen[nw + st] <= k){
nw += st;
k -= fen[nw];
}
}
return nw - 2;
}
};
Fenwick On, Sum;
void Add(int id, int del){
// cerr << "# " << id << ' ' << del << '\n';
int pos = ridx[id];
On.Add(pos, del);
Sum.Add(pos, A[id].S * del);
}
int L = 1, R = 0; // []
ll Get(int lq, int rq){
if(rq - lq + 1 < m) return -Inf;
while(R < rq) Add(++R, 1);
while(L > lq) Add(--L, 1);
while(R > rq) Add(R--, -1);
while(L < lq) Add(L++, -1);
// cerr << '\n';
// debug(On.GetK(m));
// for(int i = 0; i < 7; i++) cerr << On.Get(i) - On.Get(i - 1) << ' ';
// cerr << '\n';
return Sum.Get(On.GetK(m)) - 2ll * (A[rq].F - A[lq].F);
}
void Solve(int l, int r, int lo, int ro){
if(r - l < 1) return ;
ll mx = -Inf, opt = lo;
int mid = (l + r) >> 1;
ll res;
for(int i = lo; i <= ro; i++){
if(i > mid) break;
res = Get(i, mid);
if(res > mx){
mx = res;
opt = i;
}
}
ans = max(ans, mx);
Solve(l, mid, lo, opt + 1);
Solve(mid + 1, r, opt, ro);
}
// naive
int OPT[N];
void NAIVE(){
for(int i = 0; i < n; i++){
ll res;
ll mx = -Inf;
for(int j = 0; j < n; j++){
if(j > i) break;
res = Get(j, i);
if(res > mx){
mx = res;
OPT[i] = j;
}
}
ans = max(ans, mx);
}
for(int i = 1; i < n; i++)
assert(OPT[i - 1] <= OPT[i]);
}
int main(){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m;
ll val, cost;
for(int i = 0; i < n; i++){
cin >> val >> cost;
A.pb({cost, val});
}
sort(all(A));
for(int i = 0; i < n; i++)
V.pb({A[i].S, i});
sort(all(V)); reverse(all(V));
for(int i = 0; i < n; i++)
ridx[V[i].S] = i;
Solve(0, n, 0, n);
// NAIVE();
// debug(Get(0, 4));
cout << ans << '\n';
// debug(Sum.Get(N - 5));
// debug(Sum.Get(78));
return 0;
}
