#include <iostream>

using namespace std;

int main(int argc, char ** argv){
  char N;
  cin >> N;
  if(N != '1'){
      cout << -1;
  }
  else{
    int digit = 0;
    while(cin >> N){
        if(N != '3'){
            cout << -1;
            break;
        }
        digit++;
    } 
    cout << digit;
  }
}