#include<cstdio>
#include<cmath>
#include<algorithm>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<cstdlib>
#include<iomanip>
#include<queue>
#include<set>

using namespace std;

string T[6] =
{
    "",
    " afkpuz",
    " bglqv.",
    " chmrw?",
    " dinsx!",
    " ejoty "
};

void Solution(string str)
{
    if ( str.size() % 2 != 0 )  //input is should be even numbers
    {
        cout<< "NA" << endl;
        return;
    }
    
    string ans = "";
    
    for (int i = 0; i < (int)str.size(); i += 2)
    {
        int first = str[i] - '0';
        int second = str[i+1] - '0';
        
        if (1 <= first && first <= 6 && 1 <= second && second <= 5 )
        {
            ans += T[second][first];
        }
        else
        {
            cout << "NA" << endl;
            return;
        }
    }
    
    cout << ans << endl;
    
}

int main()
{
    string str;
    
    while(cin>>str)
    {
        Solution(str);
    }

    return 0;
}