C # Calculates the day ordinal of a year

int y, d, M;
int m1 = to, M2 = 31, M3 = To, M4 =, M5 = To, M6 =, M7 = to, M8 = to, M9 =, M10 =, M11 =--M12
Console.WriteLine ("Please enter the Year");
y = Convert.ToInt32 (Console.ReadLine ());
If (y% 400 = = 0 | | (y% 4 = = 0 && y% 100! = 0))
{
m2 = 29;
}
Console.WriteLine ("Please enter the month (input not will be treated as default 1)");
m = Convert.ToInt32 (Console.ReadLine ());
if (M > | | m < 1)
{
m = 1;
}

Console.WriteLine ("Please enter a date (the input will not be treated as default 1)");
D = Convert.ToInt32 (Console.ReadLine ());

Switch (m)
{
Case 1:

if (D > M1 | | d < 1)
{
D = 1;
}
Console.WriteLine (Y + "year" + d.tostring () + "Day");
Break
Case 2:

if (d> m2 | | d < 1)
{
D = 1;
}
Console.WriteLine (Y + "year" + (M1 + D). ToString () + "Day");
Break
Case 3:

if (d > M3 | | d < 1)
{
D = 1;
}
Console.WriteLine (Y + "year" + (M1 + m2 + d). ToString () + "Day");
Break
Case 4:

if (d > M4 | | d < 1)
{
D = 1;
}
Console.WriteLine (Y + "year" + (M1 + m2 + m3 + d). ToString () + "Day");
Break

Case 5:

if (d > M5 | | d < 1)
{
D = 1;
}
Console.WriteLine (Y + "year" + (M1 + m2 + m3 + m4 + D). ToString () + "Day");
Break
Case 6:

if (d > M6 | | d< 1)
{
D = 1;
}
Console.WriteLine (Y + "year" + (M1 + m2 + m3 + M4 + M5 + D). ToString () + "Day");
Break
Case 7:

if (d > M7 | | d < 1)
{
D = 1;
}
Console.WriteLine (Y + "year" + (M1 + m2 + m3 + M4 + M5 + M6 + D). ToString () + "Day");
Break
Case 8:

if (d > M8 | | d < 1)
{
D = 1;
}
Console.WriteLine (Y + "year" + (M1 + m2 + m3 + M4 + M5 + M6 + M7 + D). ToString () + "Day");
Break
Case 9:

if (d> M9 | | D < 1)
{
D= 1;
}
Console.WriteLine (Y + "year" + (M1 + m2 + m3 + M4 + M5 + M6 + M7 + m8 + D). ToString () + "Day");
Break
Case 10:

if (d > M10 | | d < 1)
{
D = 1;
}
Console.WriteLine (Y + "year" + (M1 + m2 + m3 + M4 + M5 + M6 + M7 + m8 + M9 + D). ToString () + "Day");
Break
Case 11:

if (d > M11 | | d < 1)
{
D = 1;
}
Console.WriteLine (Y + "year" + (M1 + m2 + m3 + M4 + M5 + M6 + M7 + m8 + M9 + M10 + D). ToString () + "Day");
Break
Case 12:

if (d > M12 | | d < 1)
{
D = 1;
}
Console.WriteLine (Y + "year" + (M1 + m2 + m3 + M4 + M5 + M6 + M7 + m8 + M9 + M10 + M11 + D). ToString () + "Day");
Break

Default
Console.WriteLine ("You entered the wrong");
Break
}

Console.ReadLine ();

C # Calculates the day ordinal of a year