Codeforces Round #461 (Div. 2) A. Cloning Toys (water problem)

A. Cloning Toys
Time limit per test
1 second
Memory limit per test
Megabytes
Input
Standard input
Output
Standard output

IMP likes he plush toy a lot.

Recently, he found a machine that can clone plush toys. Imp knows that if he applies the machine to a original toy, he additionally gets one more original toy and one copy, and If he applies the machine to a copied toy, he gets both additional copies.

Initially, IMP has only one original toy. He wants to know if it's possible to use machine to get exactly x copied toys and y original toys? He can ' t throw toys away, and he can ' t apply the machine to a copy if he doesn ' t currently has any copies.
Input

The only line contains integers x and y (0≤x, y≤109)-the number of copies and the number of original Toys IMP WA NTS to get (including the initial one).
Output

Print "Yes", if the desired configuration is possible, and "No" otherwise.

You can print the arbitrary case (upper or lower).
Examples
Input

6 3

Output

Yes

Input

4 2

Output

No

Input

1000 1001

Output

Yes

Note

In the first example, IMP had to apply the machine twice to original toys and then twice to copies.

Although this problem is not difficult, there are many details to consider, the code will reflect

#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define inf 0x3f3f3f3f
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rep1(i,a,b) for(int i=a;i>=b;i--)
#define rson rt<<1|1,m+1,r
#define lson rt<<1,l,m
using namespace std;
const int N=1e5;
int arr[N];
int main()
{
    ios::sync_with_stdio(false);
    int x,y;
    cin>>y>>x;
    if(x==1&&y>0||x==0)
    {
        cout<<"No"<<endl;
        return 0;
    }
    int c=x-1;
    y-=c;
    if(y>=0&&y%2==0)
        cout<<"Yes"<<endl;
    else
        cout<<"No"<<endl;
    return 0;
}