#include<bits/stdc++.h>
#include<fstream>
//#include "factories.h"
using namespace std;
ifstream fin("sus.in");
ofstream fout("sus.out");
#define ll long long
#define vt vector
#define pb push_back
#define fi first
#define se second
#define forr(i, a, b) for(int i = a; i < b; i++)
#define dorr(i, a, b) for(int i = a; i >= b; i--)
#define pii pair<int, int>
#define pll pair<ll, ll>
const int x[4] = {1, -1, 0, 0};
const int y[4] = {0, 0, 1, -1};
#define int long long
const int mxn = 2e5, mxv = 1e6;
int n, m, l = 0, r = 0;
ll d[mxn + 1];
vt<ll>b;
struct th{
ll v, c;
bool operator <(const th &b){
return(c < b.c);
}
};
struct BIT{
ll bit[mxn + 1];
void upd(int p, ll v){
p--;
while(p <= mxn) {
bit[p] += v; p |= (p + 1);
}
}
ll get(int p){
ll ans = 0;
while(p){
ans += bit[p - 1]; p &= (p - 1);
}
return(ans);
}
int kth(int x){
int pos = 0;
for(int i = (1 << 17); i; i >>= 1){
if(pos + i <= mxn && bit[pos + i - 1] < x){
pos += i; x -= bit[pos - 1];
}
}
return(pos);
}
};
BIT sm, cnt;
th a[mxn + 1];
void add(int x){
//cout << a[x].v << " ";
cnt.upd(a[x].v, 1); sm.upd(a[x].v, b[a[x].v - 1]);
}
void rem(int x){
cnt.upd(a[x].v, -1); sm.upd(a[x].v, -b[a[x].v - 1]);
}
ll get(){
int p = cnt.kth(m) + 1; assert(p < mxn);
ll ans = sm.get(p - 1), lft = m - cnt.get(p - 1);
ans += b[p - 1] * lft;
//cout << ans << " ";
return(ans);
}
void solve(int le, int ri, int bestl, int bestr){
if(le > ri)return;
int mid = (le + ri) >> 1;
while(l > mid)add(--l);
while(l < mid)rem(l++);
ll pos = bestr, val = -1e18;
for(int i = bestl; i <= bestr; i++){
if(i - mid + 1 < m)continue;
while(r < i)add(++r); while(r > i)rem(r--);
ll cr = get() -2 * (a[i].c - a[mid].c);
//cout << l << ' ' << r << " " << get() << "\n";
if(cr > val){
val = cr; pos = i;
}
}
//cout << pos << ' ';
d[mid] = val;
solve(le, mid - 1, bestl, pos);
solve(mid + 1, ri, pos, bestr);
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m;
forr(i, 0, n){
cin >> a[i].v >> a[i].c;
b.pb(a[i].v);
}
sort(b.rbegin(), b.rend());
for(int i = 0; i < n; i++){
int le = 0, ri = b.size() - 1, res;
while(le <= ri){
int mid = (le + ri) >> 1;
if(b[mid] >= a[i].v){
res = mid; le = mid + 1;
}else{
ri = mid - 1;
}
}
a[i].v = res + 1;
}
sort(a, a + n);
add(0);
solve(0, n - 1, 0, n - 1);
ll ans = -1e18;
for(int i = 0; i + m - 1 < n; i++){
//cout << d[i] << " ";
ans = max(ans, d[i]);
}
cout << ans;
}
