#include<bits/stdc++.h>
using namespace std;
#define int long long
using pii=pair<int,int>;
string to_string(string s) { return s; }
template <typename T> string to_string(T v) {
bool first = true;
string res = "[";
for (const auto &x : v) {
if (!first)
res += ", ";
first = false;
res += to_string(x);
}
res += "]";
return res;
}
template <typename A, typename B>
string to_string(pair<A, B> p) {
return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
void dbg_out() { cout << endl; }
template <typename Head, typename... Tail> void dbg_out(Head H, Tail... T) {
cout << ' ' << to_string(H);
dbg_out(T...);
}
#ifdef DEBUG
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif
const int INFINI=(int)1000*1000*1000*1000*1000*1000;
int nbPossi,tailleCol,prix,benef,rep;
vector<pair<int,int>> possi;
int somMax(int deb,int fin,int nbVal) {
vector<pii> sousTab(possi.begin()+deb,possi.begin()+fin+1);
sort(sousTab.begin(),sousTab.end(),[] (pii a,pii b){
return a.second>b.second;
});
int somme=0;
for (int i=0;i<nbVal;i++) {
somme+=sousTab[i].second;
}
return somme;
}
int calcMeil(int deb,int fin) {
return possi[deb].second+possi[fin].second-2*(possi[fin].first-possi[deb].first)+somMax(deb+1,fin-1,tailleCol-2);
}
void calc(int minDeb,int maxDeb,int minFin,int maxFin) {
if (maxDeb<minDeb or maxFin<minFin) {
return;
}
int deb=(minDeb+maxDeb)/2;
pii record={-INFINI,maxFin};
dbg(deb);
for (int i=minFin;i<=maxFin;i++) {
if (i-deb+1>=tailleCol) {
dbg(deb,i);
record=max(record,{calcMeil(deb,i),i});
}
}
rep=max(rep,record.first);
calc(minDeb,deb-1,minFin,record.second);
calc(deb+1,maxDeb,record.second,maxFin);
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
cin>>nbPossi>>tailleCol;
for (int i=0;i<nbPossi;i++) {
cin>>benef>>prix;
possi.push_back({prix,benef});
}
sort(possi.begin(),possi.end());
rep=-INFINI;
calc(0,nbPossi-1,0,nbPossi-1);
cout<<rep<<endl;
return 0;
}
