#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef long double ld;
const ll MOD=1e9+7;
const ll N=2e5+5;
const ld pi=3.14159265359;
const ll INF=(1LL<<62);
#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define setp setprecision
#define lwb lower_bound
#define SZ(a) (ll)a.size()
ll n,m,val[N],c[N],tmp,ans;
vector<ll> v;
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>n>>m;
REP(i,n)cin>>val[i]>>c[i];
REP(i,n){
REP(j,n){
if(i==j)continue;
v.clear();tmp=0;
REP(k,n){
if(k==i||k==j)continue;
if(c[k]>=min(c[i],c[j])&&c[k]<=max(c[i],c[j]))v.pb(val[k]);
}
if(SZ(v)<m-2)continue;
sort(v.rbegin(),v.rend());
REP(k,m-2)tmp+=v[k];
ans=max(ans,val[i]+val[j]+tmp-2*abs(c[i]-c[j]));
}
}
cout<<ans<<"\n";
return 0;
}
