#include <iostream>
#include <string>

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;
}