def main():
    l, r, c = map(int, input().split())
    r = min(r, l + 1000)
    ans = 1000
    for i in range(l, r+1):
        cost = i * c
        if cost % 1000 == 0:
            ans = 0
        else:
            ans = min(ans, 1000 - cost % 1000)
    print(ans)
main()