#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pll;
ll inf=1000000000000000000;
int main(){
  ll n;cin>>n;
  ll a[n],b[n];
  vector<pll> v;
  for(ll i=0;i<n;i++){
    cin>>a[i]>>b[i];
    v.push_back(make_pair(b[i],a[i]));
  }
  sort(v.begin(),v.end(),greater<pll>());
  ll u;
  if(n%3==0)u=n/3*2;
  else if(n%3==1)u=(n-1)/3*2+1;
  else u=(n+1)/3*2;
  ll dp[n][n+1];
  for(ll i=0;i<n;i++)fill(dp[i],dp[i]+n+1,inf);
  dp[0][0]=0;
  dp[0][1]=v[0].first;
  for(ll i=1;i<n;i++){
    for(ll j=0;j<=i+1;j++){
      dp[i][j]=dp[i-1][j];
      if(j==0)continue;
      dp[i][j]=min(dp[i][j],dp[i-1][j-1]+v[i].second+v[i].first*(j-1));
    }
  }
  cout<<dp[n-1][u]<<endl;
  //for(ll i=0;i<n;i++){
    //for(ll j=0;j<=i+1;j++)cout<<dp[i][j]<<" ";
    //cout<<endl;
  //}
}