#include<bits/stdc++.h>
using namespace std;
#define int long long
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define pb push_back
#define sz(x) (int)(x.size())
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
#define vi vector<int>
#define vp vector<pii>
#define vvi vector<vi>
#define ykh mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count())
#define __lg(x) 63-__builtin_clzll(x)
#define pow2(x) (1LL<<x)
void __print(int x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef local
void setio(){freopen("/Users/iantsai/Library/Mobile Documents/com~apple~CloudDocs/cpp/Empty.md","r",stdin);}
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
void setio(){}
#define debug(x...)
#endif
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
struct line{
int a,b;
int operator()(const int x)const{
return a*x+b;
}
};
bool check(line l1,line l2,line l3){
return (l3.b-l2.b)*(l1.a-l2.a)<=(l2.b-l1.b)*(l2.a-l3.a);
}
const int mxn=2e5+5;
pii V[mxn];
int root[mxn];
vector<int>temp;
struct SegTree{
int l,r,sum,c;
};
SegTree seg[mxn<<5];
int cnt;
int build(int l,int r){
int node=++cnt;
seg[node].sum=0;
seg[node].c=0;
if(l==r){
return node;
}
int mm=l+r>>1;
seg[node].l=build(l,mm);
seg[node].r=build(mm+1,r);
return node;
}
int update(int from,int l,int r,int p,int v){
int node=++cnt;
seg[node]=seg[from];
if(l==r){
seg[node].c++;
seg[node].sum+=v;
return node;
}
int mm=l+r>>1;
if(p<=mm){
seg[node].l=update(seg[node].l,l,mm,p,v);
}
else{
seg[node].r=update(seg[node].r,mm+1,r,p,v);
}
seg[node].sum=seg[seg[node].l].sum+seg[seg[node].r].sum;
seg[node].c=seg[seg[node].l].c+seg[seg[node].r].c;
return node;
}
int query(int v,int u,int l,int r,int k){
if(l==r){
return min(seg[u].c-seg[v].c,k)*temp[l-1];
}
int mm=l+r>>1;
int x=seg[seg[u].r].sum-seg[seg[v].r].sum;
int y=seg[seg[u].r].c-seg[seg[v].r].c;
if(y>=k){
return query(seg[v].r,seg[u].r,mm+1,r,k);
}
else{
return x+query(seg[v].l,seg[u].l,l,mm,k-y);
}
}
int P,m;
int calc(int l,int r){
return 2*V[l].F-2*V[r].F+query(root[l-1],root[r],1,P,m);
}
int ans=0;
void go(int l,int r,int ql,int qr){
if(r<l){
return;
}
int mm=l+r>>1;
int mx=-8e18,best=ql;
for(int i=ql;i<=qr and i+m-1<=mm;i++){
int x=calc(i,mm);
debug(i,mm,x);
if(x>mx){
mx=x;
best=i;
}
}
chmax(ans,mx);
go(l,mm-1,ql,best);
go(mm+1,r,best,qr);
}
signed main(){
setio();
ios::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
int n;
cin>>n>>m;
for(int i=1;i<=n;i++){
cin>>V[i].S>>V[i].F;
temp.pb(V[i].S);
}
sort(all(temp));
temp.resize(unique(all(temp))-temp.begin());
P=sz(temp);
sort(V+1,V+n+1);
root[0]=build(1,P);
for(int i=1;i<=n;i++){
int x=lower_bound(all(temp),V[i].S)-temp.begin()+1;
root[i]=update(root[i-1],1,P,x,temp[x-1]);
}
go(m,n,1,n);
cout<<ans<<'\n';
}
/*
input:
*/
