#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int n,k;
ll a[100005],b[100005];
ll f(ll x)
{
    ll s=0ll;
    int i;
    vector<ll>v;
    for(i=0;i<n;i++)
    {
        ll aa=abs(a[i]-x)+b[i];
        v.push_back(aa);
    }
    sort(v.begin(),v.end());
    for(i=0;i<k;i++)
    {
        s+=v[i];
    }
    return s; 
}
int main()
{
    cin>>n>>k;
    int i;
    for(i=0;i<n;i++)
    {
        cin>>a[i]>>b[i];
    }
    ll ok=-1e9,ng=1e9;
    while(abs(ok-ng)>1)
    {
        ll mi=(ok+ng)/2;
        ll u1=f(mi);
        ll u2=f(mi+1);
        if(u1>=u2)
        {
            ok=mi;
        }
        else 
        {
            ng=mi;
        }
    }
    cout<<f(ok+1)<<endl;
}