#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#define int long long
#define ii pair<int,int>
#define fir first
#define sec second
#define pb push_back
const int maxn=2e5;
int n,m;
ii apa[maxn+2];
int ans=-1e18;
struct seg{
int cnt,sum,l,r;
seg *lf,*rg;
void build(int x,int y){
l=x,r=y;
if(l==r){
cnt=sum=0;
return;
}
int mid=(l+r)/2;
lf=new seg(),rg=new seg();
lf->build(l,mid),rg->build(mid+1,r);
cnt=sum=0;
}
void update(int pos,int val,int bny){
if(l==r){
sum+=val,cnt+=bny;
return;
}
int mid=(l+r)/2;
if(mid>=pos)lf->update(pos,val,bny);
else rg->update(pos,val,bny);
sum=lf->sum+rg->sum;
cnt=lf->cnt+rg->cnt;
}
ii query(int posl,int posr){
if(l>=posl && r<=posr)return {sum,cnt};
if(l>posr || r<posl)return {0,0};
ii b=rg->query(posl,posr);
ii a=lf->query(posl,posr);
return {a.fir+b.fir,a.sec+b.sec};
}
int walk(int brp){
if(l==r)return (sum/cnt)*brp;
if(rg->cnt>=brp){
return rg->walk(brp);
}
int tot=rg->sum;
tot+=lf->walk(brp-rg->cnt);
return tot;
}
};
vector<int>comp;
seg cek;
int pos(int val){
int idx=lower_bound(comp.begin(),comp.end(),val)-comp.begin()+1;
return idx;
}
int posl,posr;
void range(int l,int r){
while(posl>l){
posl--;
int mana=pos(apa[posl].sec);
cek.update(mana,apa[posl].sec,1);
}
while(posl<l){
int mana=pos(apa[posl].sec);
cek.update(mana,-apa[posl].sec,-1);
posl++;
}
while(posr>r){
int mana=pos(apa[posr].sec);
cek.update(mana,-apa[posr].sec,-1);
posr--;
}
while(posr<r){
posr++;
int mana=pos(apa[posr].sec);
cek.update(mana,apa[posr].sec,1);
}
}
void dnc(int l,int r,int optl,int optr){
if(l>r)return;
int mid=(l+r)/2;
int mx=-1e18,opt=optl;
for(int q=max(optl,mid+(m-1));q<=optr;q++){
range(mid+1,q-1);
int brp=cek.walk(m-2)+2*apa[mid].fir-2*apa[q].fir;
//cout<<apa[q].fir<<endl;
brp+=apa[mid].sec+apa[q].sec;
if(mx<brp){
mx=brp;
opt=q;
}
}
ans=max(ans,mx);
dnc(l,mid-1,optl,opt),dnc(mid+1,r,opt,optr);
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin>>n>>m;
for(int q=1;q<=n;q++){
cin>>apa[q].sec>>apa[q].fir;
}
sort(apa+1,apa+n+1);
for(int q=1;q<=n;q++){
comp.pb(apa[q].sec);
}
sort(comp.begin(),comp.end());
comp.erase(unique(comp.begin(),comp.end()),comp.end());
cek.build(1,comp.size());
posl=1,posr=0;
dnc(1,n,1,n);
cout<<ans<<endl;
}
