CF1073A.Diverse Substring

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题目描述

You are given a string ss , consisting of nn lowercase Latin letters.

A substring of string ss is a continuous segment of letters from ss . For example, "defor" is a substring of "codeforces" and "fors" is not.

The length of the substring is the number of letters in it.

Let's call some string of length nn diverse if and only if there is no letter to appear strictly more than n2\frac n 2 times. For example, strings "abc" and "iltlml" are diverse and strings "aab" and "zz" are not.

Your task is to find any diverse substring of string ss or report that there is none. Note that it is not required to maximize or minimize the length of the resulting substring.

输入格式

The first line contains a single integer nn ( 1n10001 \le n \le 1000 ) — the length of string ss .

The second line is the string ss , consisting of exactly nn lowercase Latin letters.

输出格式

Print "NO" if there is no diverse substring in the string ss .

Otherwise the first line should contain "YES". The second line should contain any diverse substring of string ss .

输入输出样例

  • 输入#1

    10
    codeforces
    

    输出#1

    YES
    code
    
  • 输入#2

    5
    aaaaa
    

    输出#2

    NO
    

说明/提示

The first example has lots of correct answers.

Please, restrain yourself from asking if some specific answer is correct for some specific test or not, these questions always lead to "No comments" answer.

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