#include <iostream>

using namespace std;

/*

  1 2 3 4 5 6

1 a f k p u z

2 b g l q v .

3 c h m r w ?

4 d i n s x !

5 e j o t y  

*/

char conv(string str) {

	int c=str[0]-'0'-1, v=str[1]-'0'-1;

	if (c<5) {

		return 'a'+5*c+v;

	} else {

		switch (v) {

			case 0:

				return 'z';

			case 1:

				return '.';

			case 2:

				return '?';

			case 3:

				return '!';

			case 4:

				return ' ';

		}

	}

}

int main() {

	string mes;

	while (cin>>mes) {

		if (mes.length()%2!=0) cout << "NA" << endl;

		else {

			string temp="", res="";

			for (int i=0; i<mes.length(); i++) {

				if (i%2!=0) {

					temp += mes[i];

					res += conv(temp);

					temp = "";

				} else temp += mes[i];

			}

			cout << res << endl;

		}

	}

}