#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;
using ll = long long;

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

    string s;
    cin>>s;
    bool fn = true;
    int n = s.size();
    for(int i = 0;i<n;i++){
        if(i==0){
            if(s[i]!='1') fn = false;
        }else{
            if(s[i]!='3') fn = false;
        }
    }
    if(fn){
        int m = s.size();
        cout<<m-1<<endl;
    }else{
        cout<<-1<<endl;
    }
}