#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;

//template
#define rep(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define ALL(v) (v).begin(),(v).end()
using ll=long long int;
const int inf = 0x3fffffff; const ll INF = 0x1fffffffffffffff; const double eps=1e-12;
template<typename T>inline bool chmax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
template<typename T>inline bool chmin(T& a,T b){if(a>b){a=b;return 1;}return 0;}

ll dp[2010][2010];

int main(){
   int n;
   cin>>n;
   
   using P=pair<int,int>;
   vector<P> a(n);
   rep(i,0,n)cin>>a[i].second>>a[i].first;

   sort(ALL(a),greater<P>());
   rep(i,0,n+4)rep(j,0,n+4)dp[i][j]=INF;
   dp[0][0]=0;
   rep(i,0,n)rep(j,0,n+1){
      chmin(dp[i+1][j],dp[i][j]);
      ll add=a[i].first*j+a[i].second;
      chmin(dp[i+1][j+1],dp[i][j]+add);
   }
   cout<<dp[n][(n/3)*2+(n%3)]<<'\n';
   return 0;
}