Score : $200$ points
Takahashi's shop sells $N$ products. The usual price of the $i$-th product is $A_i$ yen (Japanese currency).
It has a bargain sale today, with a discount of $1$ yen off the usual prices for the $2$-nd, $4$-th, and the subsequent even-indexed products. The $1$-st, $3$-rd, and the subsequent odd-indexed products are sold for their usual prices.
You have $X$ yen. Can you buy all the $N$ products with this money?
Input is given from Standard Input in the following format:
$N$ $X$ $A_1$ $A_2$ $\ldots$ $A_N$
If you can buy all the $N$ products, print Yes; otherwise, print No.
2 3 1 3
Yes
You can buy the $1$-st product for $1$ yen and the $2$-nd product for $2$ yen, $1$ yen off the usual price. You have just enough money, $3$ yen, to buy both of them.
4 10 3 3 4 4
No
You can buy these four products for $3$ yen, $2$ yen, $4$ yen, and $3$ yen, respectively. You need $12$ yen to buy all of them, and since you have only $10$ yen, you cannot buy all of them.
8 30 3 1 4 1 5 9 2 6
Yes