from exceptions import MustContainAtSymbolError, NameTooShortError, InvalidDomainError

possible_domains = [".com", ".bg", ".org", ".net"]

while True:
    data = input()
    if data == "End":
        break
    
    email = data
    
    email_prats = email.split("@")
    if len(email_prats) != 2:
        raise MustContainAtSymbolError("Email must contain @")
        
    name, second_part = email_prats
    
    if len(name) <= 4:
        raise NameTooShortError(- "Name must be more than 4 characters")
        
    domain = f".{second_part.split('.')[-1]}"
    
    if domain not in possible_domains:
        raise InvalidDomainError(f"Domain must be one of the following: {', '.join(possible_domains)}")
        
        
    print("Email is valid")