static bool TinhNamNhuan(int a)
if (a % 400 == 0 || a % 4 == 0 && a % 100 != 0)
static int TinhNgay(int a,int b, int c)
for (int i=1 ; i< b; i++)
if (b == 1 || b == 3 || b == 5 || b == 7 || b == 8 || b == 10)
else if (b == 4 || b == 6 || b == 9 || b == 11)
if (TinhNamNhuan(c)==true)
public static void Main()
Console.WriteLine("Nhap a =");
int a = int.Parse(Console.ReadLine());
Console.WriteLine("Nhap b =");
int b = int.Parse(Console.ReadLine());
Console.WriteLine("Nhap c =");
int c = int.Parse(Console.ReadLine());
var KQ = TinhNgay(a, b, c);