#include <bits/stdc++.h>
using namespace std;
using lint = long long;
template<class T = int> using V = vector<T>;
template<class T = int> using VV = V< V<T> >;

int main() {
  cin.tie(nullptr); ios::sync_with_stdio(false);
  int n; cin >> n;
  V<lint> a(n), b(n); for (int i = 0; i < n; ++i) cin >> a[i] >> b[i];
  V<> idx(n);
  iota(begin(idx), end(idx), 0);
  sort(begin(idx), end(idx), [&](int i, int j) { return b[i] > b[j]; });
  V<lint> dp(n / 3 + 1, 9e18);
  dp[0] = 0;
  for (int i = 0; i < n; ++i) {
    V<lint> ndp(n / 3 + 1, 9e18);
    for (int x = 0; x <= n / 3; ++x) {
      ndp[x] = min(ndp[x], dp[x] + a[idx[i]] + b[idx[i]] * (i - x));
      if (x) ndp[x] = min(ndp[x], dp[x - 1]);
    }
    swap(dp, ndp);
  }
  cout << dp.back() << '\n';
}