#include<bits/stdc++.h>
using namespace std;
int main(){
	string S;cin>>S;
    if(S.size()==1){
        cout<<-1<<endl;
        return 0;
    }else if(S.at(0)=='1'&&S.at(1)=='3'){
		int count=1;
		for(int i=2;i<S.size();i++){
			if(S.at(i)=='3'){
				count++;
			}else{
                cout<<-1<<endl;
                return 0;
            }
		}cout<<count<<endl;
	}else{
		cout<<-1<<endl;
	}
}