#include <iostream>
#include <string>
#include <algorithm>
#include <cctype>

int main(){
    std::string s;
    std::getline(std::cin, s);
    if (s.empty()) {
        std::cout << "Invalid input" << std::endl;
        return 0;
    }
    for (char c : s){
        id (std::isdigit(c)){
            std::cout << "Invalid input" << std::endl;
            return 0;
        }
    }
    s.erase(std::remove)(s.begin(), s.end(), ''), s.end());
    std::cout << s << std::endl;
    return 0;
}