KU01: balance

#include <bits/stdc++.h>

using namespace std;
const int N = 1e3 + 10;
int A[N], L[N], B[N], R[N];
int ans = 0;

int f(int u){
    int l = A[u] == 1 ? L[u]: f(L[u]);
    int r = B[u] == 1 ? R[u]: f(R[u]);
    ans += abs(l - r);
    return 2 * max(l, r);
}

int main(){

    int n;
    scanf("%d", &n);

    for(int i=1;i<=n;i++){
        scanf("%d %d %d %d", &A[i], &L[i], &B[i], &R[i]);
    }

    f(1);

    printf("%d", ans);

    return 0;
}