#include <bits/stdc++.h>
using namespace std;
int main() {
  char a[7][7] = {"",       "*abcde", "*fghij", "*klmno",
                  "*pqrst", "*uvwxy", "*z.?! "};
  char s[200];
  while (~scanf("%s", s)) {
    if (strlen(s) % 2 == 1)
      printf("NA\n");
    else {
      for (int i = 0; i < strlen(s); i += 2) {
        printf("%c", a[s[i] - 48][s[i + 1] - 48]);
      }
      printf("\n");
    }
  }
  return 0;
}
