#include <iostream> using namespace std; int main() { int n; cin >> n; long long ans = 0; int min_price = 1000000; // 初始设很大的值 for (int i = 1; i <= n; i++) { int a, b; cin >> a >> b; if (b < min_price) { min_price = b; } ans += 1LL * a * min_price; } cout << ans << endl; return 0; }