#include<bits/stdc++.h>
using namespace std;

int main(){
    string s; cin >> s;
    if(s[0]!='1') cout << -1 << endl;
    bool flag = false;
    for(int i=1;i<s.length();i++) if(s[i]!='3') flag = true;
    if(flag) cout << -1 << endl;
    else cout << s.length()-1 << endl;
    return 0;
}