from typing import Tuple


def validate_input(L: int, R: int, C: int) -> Tuple[int, int, int]:
    """
    引数のバリデーションを行う関数
    """
    assert 1 <= L <= R, f"Invalid L: {L}"
    assert L <= R <= 10**9, f"Invalid R: {R}"
    assert 1 <= C <= 10**9, f"Invalid C: {C}"
    return L, R, C


def min_change(L: int, R: int, C: int) -> int:
    """
    お釣りの最小値を求める関数
    """
    L, R, C = validate_input(L, R, C)
    min_change = 1000

    for x in range(L, R + 1):
        cost = x * C
        change = 1000 - cost % 1000
        if cost % 1000 == 0:
            return 0
        if change < min_change:
            min_change = change

    return min_change if min_change != 1000 else 0


L, R, C = map(int, input().split())
print(min_change(L, R, C))