n, m = map(int, input().split())
A = list(map(int, input().split()))

A.sort()

ans = []
for i in range(n-1):
    a = A[i+1] - A[i]
    ans.append(a * a)

ans.sort()

answer = []
for i in range(m-1):
    answer.append(ans[i])

print(sum(answer))