#include <bits/stdc++.h>
using namespace std;
int main() {
  string str;
  char hyou[6][7];
  hyou[1][6] = 'z';
  hyou[2][6] = '.';
  hyou[3][6] = '?';
  hyou[4][6] = '!';
  hyou[5][6] = ' ';
  for (int i = 1; i <= 5; i++) {
    for (int j = 1; j <= 5; j++) {
      hyou[i][j] = 'a' + (j - 1) * 5 + i - 1;
    }
  }
  while (cin >> str) {
    if (str.size() % 2 != 0) {
      cout << "NA" << endl;
      continue;
    }
    for (int i = 0; i < str.size(); i += 2) {
      cout << hyou[str[i + 1] - '0'][str[i] - '0'];
    }
    cout << endl;
  }
  return (0);
}
