#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

int a, b;

int main() {
  cin >> a >> b;
  if (a > b) {
    cout << 2000000000 - b - 1 << endl;
  } else {
    cout << b - 2 << endl;
  }
  return 0;
}