#include <bits/stdc++.h>
using namespace std;
template<typename T1, typename T2>
inline bool chmin (T1& a, T2 b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
int main() {
  int n;
  cin >> n;
  vector<pair<long long, long long>> ba(n);
  for (int i = 0; i < n; i++) {
    long long a, b;
    cin >> a >> b;
    ba[i] = {b, a};
  }
  sort(ba.begin(), ba.end(), greater<decltype(ba)::value_type>());
  ba.insert(ba.begin(), {0, 0});
  constexpr long long inf = 1LL << 60;
  vector<long long> dp(n + 1, inf);
  dp[0] = 0;
  for (int i = 1; i <= n; i++) {
    auto [b, a] = ba[i];
    for (int j = i; j >= 1; j--) {
      chmin(dp[j], dp[j - 1] + a + (j - 1) * b);
    }
  }
  cout << dp[(2 * n + 2) / 3] << endl;
  return 0;
}