#include<iostream>
#include<string>
#include<cctype>
#include<algorithm>
using namespace std;
int main()
{
    string input;
    getline(cin,input);
    if(input.empty()){
        return 0;
    }
    bool hasNumber =false;
    string result ="";
    for(char c:input){
        if(isdigit(c)){
            hasNumber =true;
            break;
        }
        if(!isspace(c)){
            result+=c;
        }
    }
    if(hasNumber){
        cout<<"Invalid input"<<endl;
    }else{
        cout<<result<<endl;
    }
    return 0;
    }
}