#include "bits/stdc++.h"

using namespace std;

const char en = '\n';
using  ll =          long long;
using ull = unsigned long long;

using B = bitset<10>;

int main(){
	ios::sync_with_stdio(false);cin.tie();

	int j;
	B b;
	for(int i=0;i<9;i++){
		cin>>j;
		b.set(j-1);
	}
	for(int i=0;i<9;i++){
		if(!b[i])
			cout<<i+1<<en;
	}
	return 0;
}