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