#include <bits/stdc++.h>
using namespace std;
char table[7][6];
int main() {
  int i, j, x, y;
  char a, b;
  string str;
  for (i = 1; i <= 6; i++) {
    for (j = 1; j <= 5; j++) {
      if (i == 1) {
        if (j == 1)
          table[i][j] = 'a';
        else if (j == 2)
          table[i][j] = 'b';
        else if (j == 3)
          table[i][j] = 'c';
        else if (j == 4)
          table[i][j] = 'd';
        else if (j == 5)
          table[i][j] = 'e';
      } else if (i == 2) {
        if (j == 1)
          table[i][j] = 'f';
        else if (j == 2)
          table[i][j] = 'g';
        else if (j == 3)
          table[i][j] = 'h';
        else if (j == 4)
          table[i][j] = 'i';
        else
          table[i][j] = 'j';
      } else if (i == 3) {
        if (j == 1)
          table[i][j] = 'k';
        else if (j == 2)
          table[i][j] = 'l';
        else if (j == 3)
          table[i][j] = 'm';
        else if (j == 4)
          table[i][j] = 'n';
        else
          table[i][j] = 'o';
      } else if (i == 4) {
        if (j == 1)
          table[i][j] = 'p';
        else if (j == 2)
          table[i][j] = 'q';
        else if (j == 3)
          table[i][j] = 'r';
        else if (j == 4)
          table[i][j] = 's';
        else
          table[i][j] = 't';
      } else if (i == 5) {
        if (j == 1)
          table[i][j] = 'u';
        else if (j == 2)
          table[i][j] = 'v';
        else if (j == 3)
          table[i][j] = 'w';
        else if (j == 4)
          table[i][j] = 'x';
        else
          table[i][j] = 'y';
      } else {
        if (j == 1)
          table[i][j] = 'z';
        else if (j == 2)
          table[i][j] = '.';
        else if (j == 4)
          table[i][j] = '!';
        else if (j == 3)
          table[i][j] = '?';
        else
          table[i][j] = ' ';
      }
    }
  }
  while (cin >> str) {
    if (str.size() % 2 == 0) {
      for (i = 0; i < str.size(); i += 2) {
        a = str[i];
        b = str[i + 1];
        x = (int)(a - '0');
        y = (int)(b - '0');
        cout << table[x][y];
      }
      cout << "\n";
    } else {
      cout << "NA" << endl;
    }
  }
  return 0;
}
