#include <iostream>
using namespace std;
typedef long long ll;

void solve()
{
    int n;
    cin >> n;
    ll a[200002], b[200002];
    for(int i = 0; i < n; i++)
    {
        cin >> a[i] >> b[i];
    }
    ll sa = 0, sb = 0;
    ll ans = 0;
    for(int i = n - 1; i >= 0; i--)
    {
        ans += max(sa * b[i], sb * a[i]);
        sa += a[i]; sb += b[i];
    }
    cout << ans << endl;
}

int main()
{
    solve();
}