The number of people on the fourth floor is 8 less than that on the third floor, which is 52.
The number of people on the third floor is 8 less than that on the second floor, which is 60.
The number of people on the second floor is 8 less than that on the first floor, which is 68.
But the third floor is not enough, so the number of people is 180+7= 187.
Well, there are eight more. The side length plus 2 is hollow again ~