def cal(a):
    a %= 1000
    if a == 0:
        a = 1000
    return a

l, r, c = map(int, input().split())

min_cost = []
for i in range(1, 1001):
    n = cal(c)
    x = 1000 - cal(i * n)
    min_cost.append(x)

if r - l <= 1000:
    l %= 1000
    r %= 1000
    print(min(min_cost[l-1: r]))
else:
    print(min(min_cost))