All Zero Sequence

题号：NC216208
时间限制：C/C++/Rust/Pascal 1秒，其他语言2秒
空间限制：C/C++/Rust/Pascal 512 M，其他语言1024 M
64bit IO Format: %lld

题目描述

You are given a sequence $A{}$ consisting of $N{}$ integers $A_1,A_2,...,A_N$ . You can perform some operations on the sequence.

In one operation, you should do the following steps in order :

Choose an integer $i{}$ such that $1\leq i\leq N$ and $A_i>0$ , then decrease $A_i$ . Decrease $A_i$ means changing $A_i$ to $A_i-1$ .
For all integer $j{}$ such that $1\leq j\leq N$ and $A_j>1$ , decrease $A_j$ .

For example, $A=[1,2,3]{}$ . In one operations, if you choose $i=3{}$ . After the first step, $A{}$ becomes $[1,2,2]{}$ . After the second step, $A{}$ becomes $[1,1,1]{}$ .

Now you are given an integer $K{}$ , your task is to determine if it is possible to make the sequence $A{}$ consists of $N{}$ zeros in no more than $K{}$ operations.

输入描述:

The first line of the input contains two integers  and , denoting the length of the sequence  and the number of operations.
The second line of the input contains  integers .

输出描述:

If it is possible to make the sequence  consists of  zeros in no more than  operations, print "Yes", otherwise print "No" (without quote).

示例1

输入

复制

2 3
2 2

输出

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Yes

示例2

输入

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2 2
2 2

输出

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No