#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  int n, m;
  cin >> n >> m;
  int x = m - 1;
  if (m > 0 && x <= n && (n == x || ((n - x) % 2 == 0 && m > 1))) {
    cout << "Yes";
  } else {
    cout << "No";
  }
}
