#include <bits/stdc++.h>
using namespace std;
int n, w[100005], p[100005], ans;
int main () {
    freopen ("asm_algo.in", "r", stdin);
    freopen ("asm_algo.out", "w", stdout);
    cin >> n >> w[1];
    for (int i = 2; i <= n; i++) {
        cin >> p[i] >> w[i];
    }
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            ans = ans + i * j * max(i, j);
        }
    }
    cout << ans << endl;
    return 0;
}