A circle $C _ { n }$ is defined by
$$x ^ { 2 } + y ^ { 2 } = 2 n ( x + y )$$
where $n$ is a positive integer.
$C _ { 1 }$ and $C _ { 2 }$ are drawn and the area between them is shaded.
Next, $C _ { 3 }$ and $C _ { 4 }$ are drawn and the area between them is shaded.
This is shown in the diagram.
This process continues until 100 circles have been drawn.
What is the total shaded area?