#include <stdio.h>
#include <assert.h>

int N;
int A[37], B[37];

int main() {
    scanf("%d", &N);
    assert(2 <= N && N <= 37);
    for (int i = 1; i < N; i++) {
        scanf("%d", &A[i]);
        assert(getchar() == ' ');
        scanf("%d", &B[i]);
        assert(getchar() == '\n');
        assert(0 <= A[i] && A[i] <= 10000);
        assert(0 <= B[i] && B[i] <= 10000);
    }
    assert(getchar() == EOF);
    return 0;
}