#include<iostream>
#include<string>
#include<cctype>
using namespace std;

int main() {
    string text;
    getline(cin, text);
    
    if (text.empty()) {
    cout<< "Invalid input" << endl;
    return 0;
    }
    
    bool hasNumbers = false;
    for (char c : text) {
        if (isdigit(c)) {
            hashNumbers= true;
            break;
        }
    }
    
    if(hasNumbers) {
        cout << "Invalid input" << endl;
        return 0;
    }
    string result = " ";
    for (char c : text) {
        if (c != ' ') {
            result += c;
        }
    }
    cout<< result << endl;
    return 0;
}