import sys
input = sys.stdin.readline

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

A.sort()
D = []
for i in range(1, n):
    D.append(A[i] - A[i - 1])
D.sort()
ans = 0
for i in range(m - 1):
    ans += D[i]**2
print(ans)