#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
int main () {
	int N;
	cin >> N;
	std::vector<P> A(N);
	for (auto& [a, b] : A) {
		cin >> a >> b;
	}
	ll ans = 0, sa = 0, sb = 0;
	for (int i = N - 1; i >= 0; i --) {
		auto [a, b] = A[i];
		ans += max(sa * b, sb * a);
		sa += a; sb += b; 
	}
	std::cout << ans << std::endl;
}