#include <bits/stdc++.h>
int main(void) {
  int i, j;
  char tmpWord1[2], tmpWord2[2];
  int tmpNum1, tmpNum2, wordlong;
  char input[250], output[150];
  char word[5][7] = {"afkpuz", "bglqv.", "chmrw?", "dinsx!", "ejoty "};
  tmpWord1[1] = '\0';
  tmpWord2[1] = '\0';
  while (scanf("%s", input) != EOF) {
    wordlong = strlen(input);
    if (wordlong % 2 == 0) {
      for (i = 0; i < wordlong / 2; i++) {
        tmpWord1[0] = input[i * 2];
        tmpNum1 = atoi(tmpWord1);
        tmpWord2[0] = input[i * 2 + 1];
        tmpNum2 = atoi(tmpWord2);
        output[i] = word[tmpNum2 - 1][tmpNum1 - 1];
      }
      output[i] = '\0';
      printf("%s\n", output);
    } else
      printf("NA\n");
  }
  return 0;
}
