#include<iostream>
#include<string>
using namespace std;
int main(){
    string st;
    getlin(cin,st);
    if(st.find("-")!=string::npos){
        cout<<"Invalid input";
        return;
    }
    string clean="";
    for(char c:input){
        if(isalnum(c))
        clean+=c;
    }
    cout<<clean;
    return 0;
}