#include <iostream>
using namespace std;
typedef long long ll;

int main()
{
    int N;
    cin >> N;
    while(N){
        if(N % 10 == 3){
            N /= 10;
        }
        else if(N % 10 == 1){
            cout << 1 << endl;
            return 0;
        }
        else break;
    }
    cout << -1 << endl;
    return 0;
}