#include <iostream>

using namespace std;

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

int main()
{
    string s;

    while (cin >> s) {
        string out;
        bool flag = true;

        for (int i = 0; i < s.size(); i += 2) {
            int col = s[i] - '0';
            int row = s[i + 1] - '0';

            if (col < 1 || col > 6 || row < 1 || row > 5) {
                cout << "NA\n";
                flag = false;
                break;
            }
            
            out.push_back(translate[row - 1][col - 1]);
        }
        if (flag)
            cout << out << endl;
    }

    return 0;
}