#include<bits/stdc++.h>
using namespace std;
const long long inf = (long long) 1e18 + 10;
const int inf1 = (int) 1e9 + 10;
#define int long long
#define dbl long double
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()
const int maxn = 2e5+10;
const int mxv = 1e9;
int n, m;
int trq[32*maxn], trs[32*maxn], f1[32*maxn], f2[32*maxn], st[maxn], perq = 0;
vector<pair<int,int>> cake;
int att(int no, int l, int r, int noant, int pos) {
if(no == 0) no = ++perq;
if(l == r) {
trq[no]++;
trs[no]+= pos;
trq[no]+= trq[noant];
trs[no]+= trs[noant];
return no;
}
int mid = (l+r)/2;
if(pos <= mid) {
f1[no] = att(f1[no],l,mid,f1[noant],pos);
f2[no] = f2[noant];
}
else {
f2[no] = att(f2[no],mid+1,r,f2[noant],pos);
f1[no] = f1[noant];
}
trq[no]= trq[f1[no]]+trq[f2[no]];
trs[no]= trs[f1[no]]+trs[f2[no]];
return no;
}
int find(int nol, int nor, int l, int r, int val) {
if(l == r) {
return val*l;
}
int mid = (l+r)/2;
//vai pra direita
if(val-(trq[f2[nor]]-trq[f2[nol]]) > 0) {
return find(f1[nol],f1[nor],l,mid,val-(trq[f2[nor]]-trq[f2[nol]]))+trs[f2[nor]]-trs[f2[nol]];
}
else {
return find(f2[nol],f2[nor],mid+1,r,val);
}
}
int ans = -inf;
void dc(int l, int r, int opl, int opr) {
if(l > r) return;
int mx = -inf;
int opt = -1;
int mid = (l+r)/2;
if(opr-mid+1 < m) {
dc(l,mid-1,opl,opr);
return;
}
for(int i = opl; i <= opr; i++) {
if(i-mid+1 < m) continue;
int qrr = find(mid == 0 ? 0 : st[mid-1],st[i],0,mxv,m) - 2*(cake[i].fr-cake[mid].fr);
if(qrr > mx) {
mx = qrr;
opt = i;
}
}
ans = max(ans, mx);
dc(l,mid-1,opl,opt);
dc(mid+1,r,opt,opr);
}
void solve() {
cin >> n >> m;
for(int i = 1; i <= n; i++) {
int v,c; cin >> v >> c;
cake.pb(mp(c,v));
}
sort(all(cake));
for(int i = 0; i < n; i++) {
st[i] = att(0,0,mxv,i == 0 ? 0 : st[i-1],cake[i].sc);
}
dc(0,n-1,0,n-1);
cout << ans << endl;
}
int32_t main() {
ios::sync_with_stdio(false); cin.tie(0);
// freopen("in.in", "r", stdin);
// freopen("out.out", "w", stdout);
int tt = 1;
// cin >> tt;
while(tt--) {
solve();
}
}
