public static void Main()
Console.WriteLine("enter day");
D = int.Parse(Console.ReadLine());
Console.WriteLine("enter month");
M = int.Parse(Console.ReadLine());
Console.WriteLine("enter year");
Y = int.Parse(Console.ReadLine());
if((M == 4 || M == 6 || M == 9 || M == 11 || M == 2 || M == 8) && D == 1)
else if ((M == 12 || M == 5 || M == 7|| M == 10) && D == 1)
if (Y % 4 == 0 && D == 1)
else if (Y % 4 != 0 && D == 1)
else if (M == 1 && D == 1)
Console.WriteLine("the date befor is {0}.{1}.{2}", D, M, Y);