#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
int main(){
	string data[6]={""," afkpuz"," bglqv."," chmrw?"," dinsx!"," ejoty "};
	string s;
	while(cin>>s){
		string ans="";
		if(s.size()%2!=0){
			cout<<"NA"<<endl;
			continue;
		}
		for(int i=0;i<s.size();i+=2){
			int x=s[i]-'0',y=s[i+1]-'0';
			if(1<=x&&x<=6&&1<=y&&y<=5){
				ans+=data[y][x];
			}else{
				cout<<"NA"<<endl;
				continue;
			}
		}
		cout<<ans<<endl;
	}
}