#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    string s;
    cin >> s;
    int n = s.size();

    int ans = n - 1;

    rep(i,n){
        if(i == 0 && s[i] != '1'){
            ans = -1; break;
        }
        if(i > 0 && s[i] != '3'){
            ans = -1;
            break;
        }
    }

    if(ans == 0)ans = -1;

    cout << ans << endl;
    return 0;
}