#include "bits/stdc++.h"

#pragma warning(disable:4996)
using namespace std;

int main() {
	string st;cin>>st;
	int answer=-1;
	if (st[0] == '1') {
		answer=0;
		int now=1;
		while (st.size() != now) {
			if (st[now] == '3') {
				answer++;
			}
			else {
				answer=-1;
				break;
			}
			now++;
		}
	}
	if(answer==0)answer=-1;
	cout<<answer<<endl;
   return 0;
}