# from collections import def readints(): return list(map(int, input().split())) def main(): N, M = readints() A = readints() A = sorted(A) ans = cur = sum((A[i+1] - A[i])**2 for i in range(M - 1)) for i in range(M - 1, N - 1): cur += (A[i+1] - A[i])**2 - (A[i+2-M] - A[i+1-M])**2 ans = min(ans, cur) print(ans) if __name__ == '__main__': # import sys # sys.setrecursionlimit(550000) # flush = lambda: sys.stdout.flush() main()