#include <iostream>
#include <algorithm>
#include <vector>

using lint = long long;
constexpr lint INF = 1LL << 60;

void solve() {
    int n;
    std::cin >> n;

    std::vector<std::pair<lint, lint>> ps(n);
    for (auto& p : ps) {
        std::cin >> p.second >> p.first;
    }
    std::sort(ps.rbegin(), ps.rend());

    std::vector<lint> dp(n + 1, INF);
    dp[0] = 0;

    for (auto [b, a] : ps) {
        for (int i = n; i > 0; --i) {
            dp[i] = std::min(dp[i], dp[i - 1] + a + b * (i - 1));
        }
    }

    std::cout << *std::min_element(dp.begin() + n - n / 3, dp.end()) << "\n";
}

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

    solve();

    return 0;
}