#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

using P = pair<int, int>;
constexpr ll inf = 1e+17;
ll dp[2005][2005];

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;
    vector<P> ba;
    for(int i = 0; i < n; ++i){
        int a, b;
        cin >> a >> b;
        ba.emplace_back(b, a);
    }
    sort(rbegin(ba), rend(ba));

    for(int i = 0; i <= n; ++i){
        for(int j = 0; j <= n; ++j){
            dp[i][j] = inf;
        }
    }
    dp[0][0] = 0;
    for(int i = 0; i < n; ++i){
        auto [b, a] = ba[i];
        for(int j = 0; j <= i; ++j){
            chmin(dp[i + 1][j], dp[i][j] + a + b * (i - j));
            chmin(dp[i + 1][j + 1], dp[i][j]);
        }
    }

    cout << dp[n][n / 3] << endl;
    
    return 0;
}