#include <bits/stdc++.h>
using namespace std;
string S, T;
int a;
char c[101] =
    "00000000000abcde00000fghij00000klmno00000pqrst00000uvwxy00000z.?! "
    "0000000000000000000000000000000000";
int main() {
  while (cin >> S) {
    T = "";
    if (S.size() % 2 == 1) {
      cout << "NA" << endl;
      goto E;
    }
    for (int i = 0; i < S.size() / 2; i++) {
      a = stoi(S.substr(i * 2, 2));
      if (c[a] == '0') {
        cout << "NA" << endl;
        goto E;
      } else {
        T += c[a];
      }
    }
    cout << T << endl;
  E:;
  }
}
