#include<list> #include<queue> #include<stack> #include<cmath> #include<cstdio> #include<cstring> #include<iomanip> #include <limits> #include<iostream> #include <conio.h> #include<algorithm> #include <windows.h> #include<bits/stdc++.h> using namespace std; int main() { int n, a, b, ndd = 101, s = 0; cin >> n; for (int i = 1; i <= n; i++) { cin >> a >> b; if (ndd > b) { ndd=b; } s += a * ndd; } cout << s; }