#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <stdio.h>
#include <cstring>
#include <queue>
#include <stack>
#include <functional>
using namespace std;
#define Would
#define you


int main() {
	int k[10];
	for (int i = 0; i < 9; ++i) {
		cin >> k[i];
		if (i == 0 && k[i] == 2) {
			cout << 1 << endl;
			return 0;
		}
		if (k[i] - 1 != k[i - 1]) {
			cout << k[i - 1] << endl;
		}
	}
}