#include <bits/stdc++.h>
#include <unordered_set>
using namespace std;
#define ll long long
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define repeat(i,s,n) for(int (i)=s; (i)<(n); (i)++)
#define revrep(i,n) for(int (i)=(n)-1;i>=0; i--)

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout<<setprecision(std::numeric_limits<float>::max_digits10);
  int n;
  cin>>n;
  vector<pair<ll,ll>> ba(n);
  rep(i,n) {
    ll a,b;
    cin>>a>>b;
    ba[i]=make_pair(b,a);
  }
  sort(ba.begin(),ba.end());
  reverse(ba.begin(),ba.end());
  const ll inf=1e18;
  auto dp = vector<vector<ll>>(n+1,vector<ll>(n+1,inf));
  dp[0][0]=0;
  rep(i,n) {
    ll a,b;
    tie(b,a)=ba[i];
    rep(j,i+2) {
      if(j-1>=0) {
        dp[i+1][j]=min(dp[i][j-1],dp[i][j]+a+b*(i-j));
      } else {
        dp[i+1][j]=dp[i][j]+a+b*(i-j);
      }
    }
  }
  cout << dp[n][n/3] << endl;
  return 0;
}