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