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

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