using System;
using System.Linq;
class Program
{
static void Main() {
int[][] array2d = {
new[] {4, 3, 3},
new[] {30, 10},
new[] {10},
new[] {1, 1, 6, 7, 7, 7, 8},
};
var arr = array2d.SelectMany(list => list)
.Distinct()
.OrderByDescending(x => x);
Console.WriteLine(string.Join(", ", arr));
}
}
/*
run:
30, 10, 8, 7, 6, 4, 3, 1
*/