#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <climits>
#include <cstring>

#define rep(i, m, n) for(int i=int(m);i<int(n);i++)
#define all(c) begin(c),end(c)

template<typename T1, typename T2>
inline void chmin(T1 &a, T2 b) { if (a > b) a = b; }

template<typename T1, typename T2>
inline void chmax(T1 &a, T2 b) { if (a < b) a = b; }

//改造
typedef long long int ll;
using namespace std;
#define INF (1 << 30) - 1
#define INFl (ll)5e15
#define DEBUG 0 //デバッグする時1にしてね
#define dump(x)  cerr << #x << " = " << (x) << endl
#define MOD 1000000007


//ここから編集する
class Solve {
public:
    int N;
    using P = pair<ll, ll>;
    vector<P> vp;

    void input() {
        cin >> N;
        vp.resize(N);
        rep(i, 0, N) {
            cin >> vp[i].first >> vp[i].second;
        }

        sort(all(vp), [](P a, P b) {
            return a.second > b.second;
        });

    }

    ll calc() {
        int final = N - N / 3;
        set<int> st;

        for (int i = 0; i < N; ++i) st.insert(i);

        //高い奴らを除去
        vector<vector<ll>> dp(N + 1, vector<ll>(N + 1, INFl));
        dp[0][0] = 0;


        for (int j = 0; j < N; ++j) {
            for (int i = j; i < N; ++i) {
                chmin(dp[i + 1][j + 1], dp[i][j]);
                chmin(dp[i + 1][j], dp[i][j] + vp[i].first + vp[i].second * (i - j));
            }
        }

        return dp[N][N / 3];
    }

    void solve() {
        input();

        ll ans = calc();
        cout << ans << endl;
    }
};


int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);

    Solve().solve();


    return 0;
}