public static void Main(string[] args)
Random rnd = new Random();
int[][] myArray = new int[rnd.Next(20)][];
for (int i = 0; i < myArray.Length; i++)
myArray[i] = new int[rnd.Next(20)];
for (int i = 0; i < myArray.Length; i++)
for (int j = 0; j < myArray[i].Length; j++)
myArray[i][j] = rnd.Next(1000);
for (int i = 0; i < myArray.Length; i++)
for (int j = 0; j < myArray[i].Length; j++)
Console.Write(myArray[i][j] + "\t");