Mr. Kitayuta's Gift

//回文判断 Codeforces Round #286 (Div. 2)
#include<iostream>
#include<cstdio> 
int main()
{
    string f,temp; cin>>f;
    int len(f.size());
    for(char c ='a';c<='z';c++)
    {
        temp.clear();
        temp.push_back(c);
        for(int i=0;i<=len;i++)
        {
            string spre = f.substr(0,i);
            string stail = f.substr(i,len-i);
            string s1 = spre + temp + stail;
            string s2 = s1;
            reverse(s2.begin(),s2.end());   //翻转字符串
            if(s1 == s2) {cout<<s1<<endl;return 0;}
        }
    }
    printf("NA\n");
    return 0;
}