#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <iostream>
#include <string>
#include <set>
#include <map>
#include <vector>
#include <queue>
#define ll long long
#define db double
using namespace std;
const ll N = 2e5 + 100;
ll sma,smb,ans,n;
ll a[N],b[N];
int main() {
	scanf("%lld",&n);
	for (ll i = 1;i <= n;i++) {
		scanf("%lld%lld",&a[i],&b[i]);
	}
	sma = smb = ans = 0;
	for (ll i = n;i > 0;i--) {
		ans += max(a[i] * smb,b[i] * sma);
		sma += a[i];
		smb += b[i];
	}
	printf("%lld",ans);
	return 0;
}