static void Main(string[] args)
{
int[] A = new int[10];
Random rand = new Random();
Console.WriteLine("До: ");
for (int i = 0; i < A.Length; i++)
{
A[i] = rand.Next(-20,20);
Console.Write("{0} ", A[i]);
}
Console.WriteLine();
Console.WriteLine("После: ");
for (int i = 0; i < A.Length; i++)
{
if ((A[i] % 4 != 0) && (i < A.Length / 2))
A[i] = A[i] - 10;
Console.Write("{0} ", A[i]);
}
Console.ReadKey();
}