#include <bits/stdc++.h>
#define int long long
#define ll long long
#define rep(i,n) for(int i=0;i<n;i++)
#define INF LLONG_MAX/3
#define eps LDBL_EPSILON
#define moder (1000000007)
#define pie acos(-1)
#define P std::pair<int,int>
#define prique priority_queue
#define ggr getchar();getchar();return 0;
using namespace std;
string s;
signed main(){
	cin>>s;
	if(s[0]!='1'||s.size()==1){
		cout<<-1<<endl;
		return 0;
	}
	for(int i=1;i<s.size();i++){
		if(s[i]!='3'){
			cout<<-1<<endl;
			return 0;
		}
	}
	cout<<s.size()-1<<endl;
	return 0;
}