#include<iostream>
#include<string>
#include<cctype>
using namespace std;
int main(){
    string t;
    getline(cin,t);
    if(t.length()==0){
        cout<<"Invalid input";
        return 0;
    }
    for(char ch:t)
    {
        if(isdigit(ch)){
            cout<<"Invalid input";
                    return 0;

        }
    }
    string result m ="";
    for(char ch : t){
        if(ch != ' '){
            result +=ch;
        }
    }
    cout<<result;
    return 0;
}