#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main(void){
    string a;
    int ans=0;
    cin>>a;
    if(a=="1"){
        cout<<-1<<endl;
    }
    if(a[0]=='1'){
        for(int i=1;i<a.size();i++){
            if(a[i]=='3'){
                ans++;
                if(i==a.size()-1){
                    cout<<ans<<endl;
                }
            }else{
                cout<<-1<<endl;
                break;
            }
        }
    }else{
        cout<<-1<<endl;
    }
    

}