#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;

int main() {
    string S; cin >> S;
    bool ok = S[0] == '1';
    int n = S.length();
    int cnt3 = count(S.begin() + 1, S.end(), '3');
    ok &= cnt3 == n - 1 && cnt3 > 0;
    if (ok) {
        cout << cnt3 << endl;
    } else {
        cout << -1 << endl;
    }
    return 0;
}