#include <iostream>
#include <regex>
using namespace std;
    int main() {
        string code;
        cin >> code;
        
        try {
            regex pattern("[A-Z0-9{4}-[A-Z0-9]{4}-[A-Z0-9]{4}$");
            
            if (regex_match(code, pattern)) {
                cout << "valid";
            } else {
                throw invalid_argument("Invalid format");
            }
            
        }
        catch (...) {
            cout << "Invalid";
        }
         return 0;   
        }
        
    }