#include <bits/stdc++.h>   using namespace std;   int main() {     int first, second;     cin >> second >> first;     if ((second == 1 && first == 0) || first == 0) {       cout <<  NO ;       return 0;     } else if (first == 1 && second == 0) {       cout <<  YES ;       return 0;     }     int tot = first;     int co = first - 1;     if (first == 1 && second >= 0) {       cout <<  NO ;       return 0;     }     if ((second - co) % 2 == 0 && (second - co) >= 0)       cout <<  YES ;     else       cout <<  NO ;   }   