while True:
        command = raw_input("\nPlease enter a command:\n")
        type(command)
        if command not in ("ADD", "SUB"):
            print ("Illegal command\n")
        else:
            print("Enter "+command+" Expression\n Ex.) 1 2")
            if command == "ADD":
                var1, var2 = [int(x) for x in raw_input("Enter two numbers here: ").split()]
                value = var1+var2
                print(value)
            if command == "SUB":
                var1, var2 = [int(x) for x in raw_input("Enter two numbers here: ").split()]
                value = var1-var2
                print(value)