To further exaplain, imagine you have three friends all with 5 money, X,Y and Z. Your function would say that X>Y, Y>Z, and Z>X. This will mean that the sort will keep sorting on and on forever, trying to get it right, but it never will because X can be greater or smaller than Y depending if it is the a parameter or b parameter.

If you set n=d=1000 and v[i].money=v[i].friendship=123 it will throw the exception.