#include <bits/stdc++.h>
const double PI = acos(-1);
using namespace std;
char in[200] = {'\0'};
char out[5][6] = {
    {'a', 'f', 'k', 'p', 'u', 'z'}, {'b', 'g', 'l', 'q', 'v', '.'},
    {'c', 'h', 'm', 'r', 'w', '?'}, {'d', 'i', 'n', 's', 'x', '!'},
    {'e', 'j', 'o', 't', 'y', ' '},
};
int main() {
  while (cin >> in) {
    int co = 0;
    for (int i = 0; i < 200; i++)
      if (in[i] != '\0') co++;
    if (co % 2) {
      cout << "NA" << endl;
      continue;
    }
    for (int i = 0; i < co; i++) {
      int a, b;
      a = in[i] - '1';
      i++;
      b = in[i] - '1';
      cout << out[b][a];
    }
    cout << endl;
    for (int i = 0; i < co; i++) in[i] = '\0';
  }
}
