Score : $300$ points
Given is a number sequence $A$ of length $N$.
Find the sum of squared differences of every pair of elements: $\displaystyle \sum_{i = 2}^{N} \sum_{j = 1}^{i - 1} (A_i - A_j)^2$.
Input is given from Standard Input in the following format:
$N$ $A_1$ $A_2$ $A_3$ $\cdots$ $A_N$
Print the answer.
3 2 8 4
56
We have $\sum_{i = 2}^{N} \sum_{j = 1}^{i - 1} (A_i - A_j)^2 = (8 - 2)^2 + (4 - 2) ^ 2 + (4 - 8) ^ 2 = 56$.
5 -5 8 9 -4 -3
950