printf("Do you want to play again?(Yes or No):");//at this point Do you want to play again?(Yes or No): 
                                                 //and Incorrect value(Y/N) are printed.
do
{
	scanf("%c", &again);
	again = (again >= 'A' && again <= 'Z') ? again + ('a' - 'A') : again;
	if (again != 'y' && again != 'n')
		printf("\nIncorrect value(Y/N)");
}while (again != 'y' && again != 'n');