N, M = map(int, input().split())

max_x = N
div_sum = [0] * (max_x + 1)

upper_d = min(M, N)
for d in range(1, upper_d + 1):
    for x in range(d, max_x + 1, d):
        div_sum[x] += d

max_mod = 0
sum_floor = 0
for x in range(1, max_x + 1):
    sum_floor += div_sum[x]
    current_mod = x * M - sum_floor
    if current_mod > max_mod:
        max_mod = current_mod

print(max_mod)