#include <bits/stdc++.h>

using namespace std;

const long long M = 2e9;

int main() {
  long long a, b;
  cin >> a >> b;

  long long c;
  if (a > b) {
    c = M - b - 1;
  } else {
    c = b - 2;
  }
  cout << c << endl;

  return 0;
}