#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  int a, b;
  cin >> a >> b;
  if (a < b) {
    cout << b - 2 << endl;
  }
  else {
    cout << 2'000'000'000 - b - 1 << endl;
  }
  return 0;
}