CF#798 A. Mike and palindrome（水题）

A. Mike and palindrome

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

Mike has a string s consisting of only lowercase English letters. He wants to change exactly one character from the string so that the resulting one is a palindrome.

A palindrome is a string that reads the same backward as forward, for example strings "z", "aaa", "aba", "abccba" are palindromes, but strings "codeforces", "reality", "ab" are not.

Input

The first and single line contains string s (1 ≤ |s| ≤ 15).

Output

Print "YES" (without quotes) if Mike can change exactly one character so that the resulting string is palindrome or "NO" (without quotes) otherwise.

Examples

input

abccaa

output

YES

input

abbcca

output

NO

input

abcda

output

YES

题意：给出一个串，能否改变其一个字符使其变为回文串。这题有两个坑点，注意一下就好了。 注意一下 abccba 和 abcba 这两种情况即可。

#include<bits/stdc++.h>
using namespace std;

const int N = 100 + 10;
char a[N];

int main()
{
    while(cin >> a)
    {
        int l = strlen(a);
        int sum = 0;
        for(int i = 0; i < l; i++)
            if(a[i] != a[l - i - 1]) sum++;
        if(l & 1 && sum == 0) sum += 2;
        printf(sum == 2 ? "YES\n" : "NO\n");
    }
}