#include<iostream>
#include<string>
#include<cctype>
using namespace std;
int main(){
    string input;
    getline(cin,input);
    for(int i=0; i<input.length();i++){
        if(input[i]=='-'){
            cout<<'Invalid input';
            return 0;
        }
    }
    string cleaned="";
    for(char c : input){
        if(isalnum(c)){
            cleaned+=c;
        }
    }
    cout<<cleaned;
    return 0;
}