#include <iostream>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <cstring>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <numeric>
#include <utility>
#include <iomanip>
#include <algorithm>
#include <functional>
using namespace std;

#define COUT(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl
#define EACH(i, s) for (__typeof__((s).begin()) i = (s).begin(); i != (s).end(); ++i)

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<class T1, class T2> ostream& operator << (ostream &s, pair<T1,T2> P)
{ return s << '<' << P.first << ", " << P.second << '>'; }
template<class T> ostream& operator << (ostream &s, vector<T> P)
{ for (int i = 0; i < P.size(); ++i) { if (i > 0) { s << " "; } s << P[i]; } return s; }
template<class T> ostream& operator << (ostream &s, vector<vector<T> > P)
{ for (int i = 0; i < P.size(); ++i) { s << endl << P[i]; } return s << endl; }
template<class T1, class T2> ostream& operator << (ostream &s, map<T1,T2> P)
{ EACH(it, P) { s << "<" << it->first << "->" << it->second << "> "; } return s << endl; }

string str;

char conv(int i, int j) {
  int ord = (i-1) * 5 + (j-1);
  if (ord >= 0 && ord < 26) return 'a' + ord;
  if (ord == 26) return '.';
  if (ord == 27) return '?';
  if (ord == 28) return '!';
  if (ord == 29) return ' ';
  if (ord >= 30) return 'N';
}


string solve() {
  int n = str.size();
  if (n & 1) return "NA";
  string res = "";
  for (int i = 0; i < n; i += 2) {
    int a = str[i] - '0', b = str[i+1] - '0';
    //cout << a << ", " << b << endl;
    if (a < 1 || a > 6) return "NA";
    if (b < 1 || b > 5) return "NA";
    char c = conv(a, b);
    res += c;
  }
  return res; 
}

int main() {
  while (cin >> str) {
    cout << solve() << endl;
  }
}
