Hi
You must use from Read() instead of ReadLine().
for (i = 0; i < 10; i++)
a[i] = Convert.ToInt32(Console.Read());
Now, You can enter 10 numbers in bellow structure and enter Enter Key in end of list.
1 2 3 4 5 6 7 8 9 10 Now Press Enter
I hope It's helpful for you