Codeforces 798A

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
题目大意：是否可以改变一个字符，使得字符串恰好为回文串。
方法：检查字符串是否为回文，记录不同记录不同位点个数。如果字符串不是回文，且不同位点为一个，输出YES;如果位点为0（也就是回文串）且串长度为奇数（可以改变最中间的那个），则输出YES;如果前两条都不满足，输出NO。
代码：

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
using namespace std;
const int N=35;
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    char s[N];
    gets(s);
    int cnt=0;
    for(int i=0;i<strlen(s);i++)
    {
        if(s[i]!=s[strlen(s)-i-1])cnt++;
    }
    if(cnt==2)cout<<"YES"<<endl;
    else 
    {
        if(cnt==0&&strlen(s)%2)cout<<"YES"<<endl; 
        else cout<<"NO"<<endl;
    }
    return 0;
}