//
//
//  Codeforces: ganariya
//  AtCoder: ganariya2525
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//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <unordered_map>
#include <climits>
#include <set>
#include <unordered_set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
#include <random>
#include <complex>
#include <regex>
#include <locale>
#include <random>
#include <type_traits>

using namespace std;

#define SHOW_VECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOW_MAP(v){std::cerr << #v << endl; for(const auto& xxx: v){std::cerr << xxx.first << " " << xxx.second << "\n";}}

using LL = long long;

//~~~~~~~~~~~~~~~~~~~~~_(＾～＾ ｣ ∠)_~~~~~~~~~~~~~~~~~~~~~

constexpr LL INF = 1e15;

int main() {

    int N;
    cin >> N;

    vector<LL> A(N), B(N);
    for (int i = 0; i < N; i++) cin >> A[i] >> B[i];

    vector<pair<LL, LL>> BA(N);
    for (int i = 0; i < N; i++) BA[i] = make_pair(B[i], A[i]);
    sort(BA.rbegin(), BA.rend());

    int buy;

    if (N % 3 == 0) {
        buy = N - N / 3;
    }
    if (N % 3 == 1) {
        buy = N - N / 3;
    }
    if (N % 3 == 2) {
        buy = (N + 1) - (N + 1) / 3;
    }

    //dp[i][j]
    //[0, i)番目の品物まででj個買うときの最小のｎ金額
    vector<vector<LL>> dp(N + 1, vector<LL>(buy + 1, INF));
    dp[0][0] = 0;

    for (int i = 0; i < N; i++) {
        for (int j = 0; j < buy; j++) {
            //買うならば
            dp[i + 1][j + 1] = min(dp[i + 1][j + 1], dp[i][j] + BA[i].second + j * BA[i].first);

            //買わないならば
            dp[i + 1][j] = min(dp[i + 1][j], dp[i][j]);
        }
    }

//    for (int i = 0; i <= N; i++) {
//        SHOW_VECTOR(dp[i]);
//    }

    cout << dp[N][buy] << endl;

    return 0;
}