start from i (0,1) and move anti-clockwise to -i (0,-1). b/c it is pi/2 it will be a semi-circle. so u end up with the left side of a circle (it is a semi circle) starting from (0,1) going through (-1,0) and finishing at (0,-1). NOTE: u must put open circles at the start and end points ie i (0,1) and -i (0,-1) b/c you can't have an argument of a single point.