#include<iostream>
#include<cctype>
using namespcae std ;
int main(){
    string name ;
    getline(cin,name);
    string result ="";
    if(name==""){
        cout<<"Invalid input";
        return 0;
    }
    for(int i =0;i<name.length();i++){
        if(name[i]!=' '){
            result+=name[i];
        }
    }
    for(int i=0;i<result.length();i++){
        if(!isalpha(result[i])){
            cout<<"Invalid input";
            return 0;
        }
    }
    for(int i=0;i<result.length();i++){
        cout<<result[i];
    }
}