# 2個の整数A, Bが与えられる(B != 0)
# AをBで割った余りを求めよ
#
# -100 <= A, B <= 100
# B != 0

import sys
import itertools
import time
from math import radians, sin, cos, tan, sqrt
from collections import deque

def input():
    return sys.stdin.readline().replace('\n','')
sys.setrecursionlimit(1000000)
md1 = 998244353
md2 = 10 ** 9 + 7

A, B = map(int, input().split())

r = A % B

if r < 0:
    while not (0 <= r and r < abs(B)):
        r += abs(B)
else:
    if 0 <= r and abs(B) <= r:
        while not(0 <= r and r < abs(B)):
            r -= abs(B)

print(r)