#include <bits/stdc++.h> using namespace std; typedef signed long long ll; #undef _P #define _P(...) (void)printf(__VA_ARGS__) #define FOR(x,to) for(x=0;x<to;x++) #define FORR(x,arr) for(auto& x:arr) #define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++) #define ALL(a) (a.begin()),(a.end()) #define ZERO(a) memset(a,0,sizeof(a)) #define MINUS(a) memset(a,0xff,sizeof(a)) //------------------------------------------------------- string S; int L; int parlin(string SS) { int i; FOR(i,SS.size()) if(SS[i]!=SS[SS.size()-1-i]) return 0; return 1; } void solve() { int i,j,k,l,r,x,y; string s; cin>>S; L=S.size(); if(parlin(S)) { string T=S.substr(0,L/2)+S[L/2]+S.substr(L/2); cout<<T<<endl; return; } FOR(i,L) { if(S[i]!=S[L-1-i]) { string T=S.substr(0,i)+S[L-1-i]+S.substr(i); if(parlin(T)) { cout<<T<<endl; return; } T=S.substr(0,L-1-i+1)+S[i]+S.substr(L-1-i+1); if(parlin(T)) { cout<<T<<endl; return; } break; } } cout<<"NA"<<endl; } int main(int argc,char** argv){ string s;int i; if(argc==1) ios::sync_with_stdio(false); FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin); solve(); return 0; }