#include<iostream>
#include<vector>
#include<algorithm>
#include<functional>
#include<queue>
#include<stack>
#include<set>
#include<map>
#include<unordered_map>
#include<climits>
#include<cstdlib>
#include<cmath>
#include<string>
#include<iomanip>
#include<bitset>

using namespace std;

#define ll long long int

ll const MOD = 1000000007;
ll const INF = (long long int)1 << 61;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    string str;
    cin >> str;

    bool ok = true;
    if(str[0] != '1'){
        ok = false;
    }
    for(int i = 1; i < str.size(); i++){
        if(str[i] != '3'){
            ok = false;
        }
    }

    if(ok && str.size() > 1){
        cout << str.size() - 1 << endl;
    }else{
        cout << -1 << endl;
    }
    
    return 0;
}