#include<iostream> 
#include<string>
using namespace std;
int main(){
    string s;
    getline(cin,s);
    string result="";
    for (int i=0;i<s.length();i++){
        if(isdigit(s[i])){
            result +=str[i];
        }
    }
    if(result.length()==0){
        cout<<-1;
    }
    else{
        cout<<result;
    }
    return 0;
    
}