using System;
public class Test
{
public static void Main()
{
Random ran = new Random();
int n = 4, m = 5;
int?[,] a = new int?[n, m];
for (int q=0; q<n; ++q)
for (int w=0; w<m; ++w)
a[q, w] = ran.Next(0, 9);
a[2, 3] = null;
for (int q=0; q<n; ++q)
{
for (int w=0; w<m; ++w)
Console.Write("{0} ", a[q, w]?.ToString() ?? ".");
Console.WriteLine();
}
}
}
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