#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

void solve() {
  ll a, b;
  cin >> a >> b;
  ll ans = 1e18;
  for (ll q = -1000; q <= 1000; q++) {
    ll r = a - b * q;
    if (0 <= r && r < abs(b))
      ans = min(ans, r);
  }
  cout << ans << '\n';
}

int main() {
  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);
  int T = 1;
  for (int t = 0; t < T; t++) {
    solve();
  }
  return 0;
}