B, M, *C = map(int, open(0).read().split())

l = min(C)
r = (sum(C) + B) // M
for _ in range(100):
    nl = (l * 2 + r) // 3
    nr = (l + r * 2 + 2) // 3
    a = sum(abs(c - nl) for c in C)
    b = sum(abs(c - nr) for c in C)
    if a < b:
        r = nr
    else:
        l = nl
print(min(sum(abs(c - l) for c in C), sum(abs(c - r) for c in C)))