#include <bits/stdc++.h>
using namespace std;
int in() {
  int x;
  cin >> x;
  return x;
}
template <typename T>
class SegTree {
 public:
  int n;
  T T_max;
  vector<T> dat;
  SegTree(int n_, T t_max) {
    int n = 1;
    T_max = t_max;
    while (n < n_) n *= 2;
    for (int i = 0; i < 2 * n - 1; i++) dat.push_back(t_max);
  }
  void update(int k, T a) {
    k += n - 1;
    dat[k] = a;
    while (k > 0) {
      k = (k - 1) / 2;
      dat[k] = min(dat[k * 2 + 1], dat[k * 2 + 2]);
    }
  }
  T query(int a, int b) { return _query(a, b, 0, 0, n); }

 private:
  T _query(int a, int b, int k, int l, int r) {
    if (r <= a || b <= l) return T_max;
    if (a <= l && r <= b)
      return dat[k];
    else {
      T vl = _query(a, b, k * 2 + 1, l, (l + r) / 2);
      T vr = _query(a, b, k * 2 + 2, (l + r) / 2, r);
      return min(vr, vl);
    }
  }
};
int main() {
  string a = " abcdefghijklmnopqrstuvwxyz.?! ";
  string b;
  while (cin >> b) {
    string ans;
    if (b.size() % 2) {
      cout << "NA" << endl;
      continue;
    }
    for (int i = 0; i < b.size(); i += 2) {
      int A = b[i] - '0';
      int B = b[i + 1] - '0';
      if (A >= 7) {
        ans = "NA";
        break;
      }
      if (B >= 6) {
        ans = "NA";
        break;
      }
      A--;
      int C = A * 5 + B;
      if (C > 30) {
        ans = "NA";
        break;
      }
      ans += a[C];
    }
    cout << ans << endl;
  }
}
