#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; //conversion //------------------------------------------ inline int toInt(string s) { int v; istringstream sin(s); sin >> v; return v; } template inline string toString(T x) { ostringstream sout; sout << x; return sout.str(); } //math //------------------------------------------- template inline T sqr(T x) { return x*x; } //typedef //------------------------------------------ typedef vector VI; typedef vector VVI; typedef vector VS; typedef pair PII; typedef long long LL; //container util //------------------------------------------ #define ALL(a) (a).begin(),(a).end() #define RALL(a) (a).rbegin(), (a).rend() #define PB push_back #define MP make_pair #define SZ(a) int((a).size()) #define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i) #define EXIST(s,e) ((s).find(e)!=(s).end()) #define SORT(c) sort((c).begin(),(c).end()) //repetition //------------------------------------------ #define FOR(i,a,b) for(int i=(a);i<(b);++i) #define REP(i,n) FOR(i,0,n) //constant //-------------------------------------------- const double EPS = 1e-10; const double PI = acos(-1.0); //debug #define dump(x) cerr << #x << " = " << (x) << endl; #define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl; bool check(string a){ for (int i = 0; i < a.size(); i++){ if (a[i] != a[a.size() - 1 - i]){ return false; } } return true; } int main() { string str; cin >> str; for (int i = 0; i < str.size(); i++){ if (str[i] != str[str.size() - 1 - i]){ string tmp = str; tmp=tmp.insert(i,1,str[str.size() - 1 - i]); if (check(tmp)){ cout << tmp << endl; return 0; } tmp = str; tmp.insert(i + 1, 1,str[str.size() - 1 - i] ); if (check(tmp)){ cout << tmp << endl; return 0; } tmp = str; tmp.insert(str.size() - 1 - i, 1,str[i] ); if (check(tmp)){ cout << tmp << endl; return 0; } tmp = str; tmp.insert(str.size() - i, 1,str[i] ); if (check(tmp)){ cout << tmp << endl; return 0; } cout << "NA" << endl; return 0; } } if (str.size() % 2 == 0){ str.insert(str.size() / 2, "a"); cout << str << endl; } else{ cout << "NA" << endl; } return 0; }