#include <bits/stdc++.h>
using namespace std;
#define int long long
vector<long long> pref;
long long cl = 0 ,cr = -1 , sz;
struct node{
long long cnt = 0 , sum =0;
node():cnt(0),sum(0){};
}seg[800001];
void build(int p,int l,int r){
if(l==r){
seg[p].cnt = 0;seg[p].sum = 0;
return ;
}
int md = (l+r)/2;
build(p*2,l,md);build(p*2+1,md+1,r);
seg[p].cnt = seg[p*2].cnt+seg[p*2+1].cnt;
seg[p].sum = seg[p*2].sum+seg[p*2+1].sum;
}
void update(int p,int l,int r,int idx,long long val){
if(l==r){
seg[p].cnt+=val;
seg[p].sum+=val*pref[l-1];
return ;
}
int md = (l+r)/2;
if(idx<=md)update(p*2,l,md,idx,val);
else update(p*2+1,md+1,r,idx,val);
seg[p].cnt = seg[p*2].cnt+seg[p*2+1].cnt;
seg[p].sum = seg[p*2].sum+seg[p*2+1].sum;
}
long long query(int p,int l,int r,long long idx){
if(l==r){
return pref[l-1]*idx;
}
int md = (l+r)/2;
if(seg[p*2+1].cnt<idx)return seg[p*2+1].sum+query(p*2,l,md,idx-seg[p*2+1].cnt);
return query(p*2+1,md+1,r,idx);
}
int k;
long long inf = 1e18;
signed main() {
ios_base::sync_with_stdio(0);cin.tie(0);
long long n;
cin>>n>>k;
vector<pair<long long,long long>> v;
for(int i = 0;i<n;i++){
long long a,b;
cin>>a>>b;
pref.push_back(a);
v.push_back({b,a});
}
sort(pref.begin(),pref.end());
pref.erase(unique(pref.begin(),pref.end()),pref.end());
sz = pref.size();sort(v.begin(),v.end());
for(int i = 0;i<n;i++){
v[i].second = lower_bound(pref.begin(),pref.end(),v[i].second)-pref.begin()+1;
}
build(1,1,sz);
auto cost = [&](int l,int r){
while(cl>l)update(1,1,sz,v[--cl].second,1);
while(cr<r)update(1,1,sz,v[++cr].second,1);
while(cl<l)update(1,1,sz,v[cl++].second,-1);
while(cr>r)update(1,1,sz,v[cr--].second,-1);
return query(1,1,sz,k)-2*(v[r].first-v[l].first);
};
int ans = -inf;
function<void(int,int,int,int)> dnc = [&](int l,int r,int optl,int optr){
if(l>r) return;
int sum=0,mid=(l+r)>>1;
pair<int,int> opt={-inf,-1};
for(int i=min(optr,mid-k+1);i>=optl;i--){
int res=cost(i,mid);ans=max(ans,res);
opt=max(opt,{res,i});
}
dnc(l,mid-1,optl,opt.second);
dnc(mid+1,r,opt.second,optr);
};
dnc(k-1,n-1,0,n-k);
cout<<ans<<endl;
return 0;
}
