Avoiding Comma Separator For The Last Value?

I am generating an output on a webpage in a format like this

({"1":"Jeff","2":"Tom","3":"Michael",})

For this, basically this is the code I am using

Response.Write("(" + "{");
//
for (Int32 i = 0; i < k.Length; i++)
{
Response.Write(Convert.ToString(k.GetValue(i)) + ",");
}
//
Response.Write("}" + ")");

Notice my output, after Michael" there is a comma which I do not want since this is the last vaue but this is appearing since , is in the for loop. How to prevent this/remove this last comma from appearing?

My output should be ({"1":"Jeff","2":"Tom","3":"Michael"}) (There's no comma after last value here)