#include <iostream> #include <algorithm> #include <vector> using namespace std; int main() { int n; cin >> n; vector<int> amounts(n); vector<int> prices(n); for (int i = 0; i < n; i++) { cin >> amounts[i]; cin >> prices[i]; } int totalCost = 0; for (int i = 0; i < n; i++) { int minPriceIndex = min_element(prices.begin(), prices.end()) - prices.begin(); totalCost += amounts[i] * prices[minPriceIndex]; } cout << totalCost << endl; return 0; }