Pillow Stacking
시간 제한3초메모리 제한1024 MB
여러 종류의 베개를 원하는 만큼 쌓아 목표 부드러움 C를 정확히 만들 수 있는지 판정한다. i번째 베개의 기여는 2^(i-1)로 나눈 값의 올림이다.
문제
Eleanor has recently lost her favorite pillow. Being very particular about her pillows, she categorizes pillows by their softness. The pillow she lost had softness , and she will be unable to sleep without this exact softness. While she has access to some other types of pillows, there may not be any of her desired softness. As a work-around, she is willing to sleep with multiple pillows in a stack. When pillows with softness are stacked together in that order, the resulting softness is equal to \[ C_1 + \left\lceil \frac{C_2}{2} \right\rceil + \left\lceil \frac{C_3}{4} \right\rceil + \ldots + \left\lceil \frac{C_k}{2^{k-1}} \right\rceil. \] In other words, the th pillow in the stack contributes of its softness, rounded up. Note that is defined as the smallest integer with .
Eleanor has a lot of money and is willing to use an unlimited amount of each pillow type she has access to. Can you help her determine if there is a way to stack pillows to reach her desired softness?
입력
The first line of input contains two integers and ( and ). indicates the number of types of pillows Eleanor has access to, and indicates the desired softness level. The next line contains integers (), indicating the softness of pillows that Eleanor has access to.
출력
If it is possible for Eleanor to stack pillows to reach softness , output YES. Otherwise, output NO.