#include <iostream>
#include <algorithm>
#include <math.h>
using namespace std;

int main(){
    string s;
  	cin >> s;
    int n = s.size();
    int ans = 0;
    for ( int i = 0; i < n; i ++ ) {
        if ( i == 0 && s[i] != '1' ) ans = -1;
        else if ( i > 0 && s[i] != '3' ) ans = -1;
    }
    if ( ans != -1 ) ans = n-1;
    cout << ans << endl;
    return 0;
}