#include <iostream>
#include <cmath>
#include <vector>
#include <stack>
#include <queue>
#include <algorithm>
#include <string>

using namespace std;

int length(int matrix[101][101], int size, int r, int n){
    if(matrix[r][1] == 1){
                    return size;
    }
    for(int i = 1; i < n+1; i++){
            if(matrix[r][i] == 1){
                            return length(matrix, size+1, i, n);
            }
    }
}

int main(){
    freopen("DATA5.txt", "r", stdin);
    freopen("OUT5.txt", "w", stdout);

    for(int i =0; i<5; i++){
            int matrix[101][101];
            memset(matrix, 0, sizeof(matrix));
            int n;
            cin >> n;
            int a, b;
            for(int j = 0; j < n; j++){
                    cin >> a >> b;
                    matrix[a][b] = 1;
            }
            int len = length(matrix, 1, 1, n+1);
            cout << len << endl;
    }    
    
    return 0;
}