#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    int n;
    cin >> n;
    vector<P> v(n);
    rep(i,n) cin >> v[i].second >> v[i].first;
    sort(v.begin(), v.end(), greater<P>());
    ll a[n], b[n];
    rep(i,n){
        a[i] = v[i].second;
        b[i] = v[i].first;
    }
    ll dp[n][n+1];
    ll INF = 1001001001001001001;
    rep(i,n)rep(j,n+1)dp[i][j] = INF;

    rep(i,n){
        if(i==0){
            dp[0][0] = 0;
            dp[0][1] = a[0];
        }else{
            rep(j,n+1){
                dp[i][j] = dp[i-1][j];
                if(j==0)continue;
                ll tmp = dp[i-1][j-1] + a[i] + b[i]*(j-1);
                dp[i][j] = min(dp[i][j], tmp);
            } 
        }
    }

    ll ans = dp[n-1][n-n/3];
    cout << ans << endl;
    return 0;
}