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