A. Cloning Toys
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Imp likes his plush toy a lot.
Recently, he found a machine that can clone plush toys. Imp knows that if he applies the machine to an original toy, he additionally gets one more original toy and one copy, and if he applies the machine to a copied toy, he gets two additional copies.
Initially, Imp has only one original toy. He wants to know if it is 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 have any copies.
Input
The only line contains two integers x and y (0 ≤ x, y ≤ 109) — the number of copies and the number of original toys Imp wants to get (including the initial one).
Output
Print "Yes", if the desired configuration is possible, and "No" otherwise.
You can print each letter in arbitrary case (upper or lower).
Examples
input
Copy
6 3
output
Copy
Yes
input
Copy
4 2
output
Copy
No
input
Copy
1000 1001
output
Copy
Yes
Note
In the first example, Imp has to apply the machine twice to original toys and then twice to copies.
题意：一个人可以通过机器进行两种操作，一种是得到copy的玩具和一个original的玩具，另一种是得到两个copy个玩具（前提是要有copy的玩具），初始有一个original的玩具，问能否得到X个copy和Y个original玩具；
思路：先得到Y个original个玩具，再看能否得到X个copy；
下面附上我的代码:
#include<cstdio>
int main()
{
int x,y;
scanf("%d %d",&x,&y);
if(y==0){
printf("No\n");
}else if(y==1){
if(x==0) printf("Yes\n");
else printf("No\n");
}else{
int s=y-1;
int q=x-s;
if(q<0){
printf("No\n");
}else if(q%2==1){
printf("No\n");
}else{
printf("Yes\n");
}
}
return 0;
}