import sys, time, random
from collections import deque, Counter, defaultdict
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
inf = 2 ** 61 - 1
mod = 998244353

a, b = mi()

for i in range(-10000, 10000):
    if 0 <= a - b * i < abs(b):
        print(a - b * i)
        exit()