#include<bits/stdc++.h>
#include <iostream>
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;
const int inf=-8e18;
int c[mxn],v[mxn],vv[mxn];
/*int bit[mxn];
vector<int>temp;
int bitnum;
void modify(int p,int v){
cout<<p<<' ';
for(;p<mxn;p+=p&-p){
bit[p]+=v;
}
}
int kth(int k){
int now=0;
for(int i=bitnum-1;i>=0;i--){
if(bit[now+(1<<i)]<k){
k-=bit[now+(1<<i)];
now+=(1<<i);
}
}
return now+1;
}*/
int n,m;
int ans;
int sum;
multiset<int>s,b;
int curl,curr;
void ins(int l,int r){
while(curl>l){
curl--;
b.insert(v[curl]);
sum+=v[curl];
if(sz(b)>m){
sum-=*b.begin();
s.insert(*b.begin());
b.erase(b.begin());
}
}
while(curr<r){
curr++;
sum+=v[curr];
b.insert(v[curr]);
if(sz(b)>m){
sum-=*b.begin();
s.insert(*b.begin());
b.erase(b.begin());
}
}
while(curl<l){
if(b.find(v[curl])==b.end()){
s.erase(s.find(v[curl]));
}
else{
int x=*prev(s.end());
//debug(x,s,b);
b.insert(x);
sum+=x;
s.erase(prev(s.end()));
b.erase(b.find(v[curl]));
sum-=v[curl];
}
curl++;
}
while(curr>r){
if(b.find(v[curr])==b.end()){
s.erase(s.find(v[curr]));
}
else{
debug(sum);
int x=*prev(s.end());
b.insert(x);
sum+=x;
debug(x);
s.erase(prev(s.end()));
b.erase(b.find(v[curr]));
sum-=v[curr];
}
curr--;
}
}
void solve(int l,int r,int ql,int qr){
if(r<l){
return;
}
//debug(l,r,ql,qr,s,b);
int mm=l+r>>1;
int best=ql,mx=inf;
for(int i=ql;i+m-1<=mm and i<=qr;i++){
//debug(curl,curr,i,mm);
ins(i,mm);
debug(i,mm,s,b,sum,c[mm],c[i]);
int x=sum-2*c[mm]+2*c[i];
if(x>mx){
best=i;
mx=x;
}
}
debug(mx);
chmax(ans,mx);
solve(l,mm-1,ql,best);
solve(mm+1,r,best,qr);
}
signed main(){
setio();
ios::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin>>n>>m;
vector<pii>temp;
for(int i=1;i<=n;i++){
cin>>v[i]>>c[i];
temp.pb({c[i],v[i]});
}
sort(all(temp));
for(int i=1;i<=n;i++){
v[i]=temp[i-1].S;
c[i]=temp[i-1].F;
}
ans=inf;
sum=v[1];
b.insert(v[1]);
curl=curr=1;
ins(1,n);
debug(s,b,sum);
solve(m,n,1,n);
cout<<ans<<'\n';
}
/*
input:
*/
