#include <iostream>
#include <cstdio>
#include <string>
using namespace std;

int main(){
	string s;
	while(cin >> s){
		if(s.size()%2!=0) {
			printf("NA\n");
			continue;
		}
		
		int now=0;
		
		while(now<s.size()){
			int a=s[now]-'0', b=s[now+1]-'0';
			int p=(a-1)*5+b-1;
			//printf("a,b,p=%d,%d,%d\n",a,b,p);
			
			if(p<=25) printf("%c", p+'a');
			else if(p==26) printf(".");
			else if(p==27) printf("?");
			else if(p==28) printf("!");
			else if(p==29) printf(" ");
			now+=2;	
		}
		
		printf("\n");
	}
	return 0;
}