#include <iostream>
#include <string>
using namespace std;
int main(){
    string input;
    cin>>input;
    string digits = "";
    for(char ch : input){
        if(isdigit(ch)){
            digits += ch;
        }
    }
    if(digit.empty()){
        cout<<-1;
    }
    else{
        cout<<digit;
    }
    return 0;
}