#include <bits/stdc++.h>
using namespace std;
long long int gcd(long long int x, long long int y) {
  if (x < y) swap(x, y);
  if (x % y == 0) return y;
  return gcd(y, x % y);
}
long long int pwm(long long int a, long long int n) {
  long long int ans = 1;
  while (n > 0) {
    if (n % 2 == 1) {
      ans = (ans * a) % 1000000007;
    }
    a = (a * a) % 1000000007;
    n /= 2;
  }
  return ans % 1000000007;
}
const int pwn = 100010;
long long int pw[pwn];
void pwtwo() {
  pw[0] = 1;
  for (int i = 1; i < pwn; i++) {
    pw[i] = (pw[i - 1] * 2) % 1000000007;
  }
}
long long int gcdExtended(long long int a, long long int b, long long int *x,
                          long long int *y);
long long int modInverse(long long int a, long long int m) {
  if (a == 1) return 1;
  long long int x, y;
  long long int g = gcdExtended(a, m, &x, &y);
  if (g != 1) {
    return -1;
  } else {
    long long int res = (x % m + m) % m;
    return res;
  }
}
long long int gcdExtended(long long int a, long long int b, long long int *x,
                          long long int *y) {
  if (a == 0) {
    *x = 0, *y = 1;
    return b;
  }
  long long int x1, y1;
  long long int gcd = gcdExtended(b % a, a, &x1, &y1);
  *x = y1 - (b / a) * x1;
  *y = x1;
  return gcd;
}
long long int fact[1010];
long long int init() {
  fact[0] = 1;
  for (int i = 1; i < 1010; i++) fact[i] = (fact[i - 1] * i) % 1000000007;
}
long long int ncr(long long int n, long long int r) {
  long long int ans = fact[n];
  ans = (ans * modInverse(fact[r], 1000000007)) % 1000000007;
  ans = (ans * modInverse(fact[n - r], 1000000007)) % 1000000007;
  return ans;
}
long long int t[42];
bool check(int x) {
  for (int i = 1; i <= 40; i++) {
    if (x == t[i] - 1) return true;
  }
  return false;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int a, b;
  cin >> a >> b;
  if (a == 1 || b == 1) {
    cout << 0 << endl;
    return 0;
  }
  if (a == b) {
    cout << 0 << endl;
    return 0;
  }
  long long int x = abs(b - a);
  long long int ans = a * b;
  ans = ans / gcd(a, b);
  long long int c = 0;
  for (int i = 1; i <= sqrt(x); i++) {
    if ((x % i) == 0) {
      long long int y = a % i;
      y = (i - y) % i;
      long long int k = (a + y) * (b + y);
      k = k / gcd(a + y, b + y);
      if (ans > k) {
        ans = k;
        c = y;
      }
      int z = x / i;
      y = a % z;
      y = (z - y) % z;
      k = (a + y) * (b + y);
      k = k / gcd(a + y, b + y);
      if (ans > k) {
        ans = k;
        c = y;
      }
    }
  }
  cout << c << endl;
  return 0;
}
