#include <bits/stdc++.h>
using namespace std;

// infty
#define ULLINF (ULLONG_MAX)
#define LLINF  (LLONG_MAX)
#define IINF   (INT_MAX)
#define INF    (1<<29)

// math
#define Sq(x) ((x)*(x))

// container utility
#define ALL(x) (x).begin(), (x).end()
#define MP make_pair
#define PB push_back
#define EACH(it,c) for(__typeof((c).begin())it=(c).begin();it!=(c).end();it++)

// rep
#define REP(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

// typedef
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;

typedef long long ll;

// pair util
#define FST first
#define SND second

// range validator
#define CK(n,a,b) (a<=n && n<b)

// conversion
template<class T> inline string toStr(T a) { ostringstream oss_; oss_ << a; return oss_.str(); }
inline int toInt(string s) { return atoi(s.c_str()); }

// prime
bool isPrime(int a) { for(int i=2; i*i <=a; i++) if(a%i == 0) return false; return true; }

int const dx[] = {-1,0,1,0,-1,1,1,-1};
int const dy[] = {0,-1,0,1,-1,-1,1,1};

//////////////////////////////////////////////////////////////


int main() {
  
  string s;
  while(cin >> s) {
    int const N = s.size();
    
    if(N%2) {
      cout << "NA" << endl;
      continue;
    }
    
    for(int i=0; i<N; i+=2) {
      int a = s[i]-'0'-1; if(!CK(a, 0, 6)) { cout << "NA" << endl; goto EXIT; }
      int b = s[i+1]-'0'-1; if(!CK(b, 0, 5)) { cout << "NA" << endl; goto EXIT; }
      
      char ch = (char)('a' + a*5+b);
      if(!CK(ch,'a','z'+1)) {
	if(b == 1 && a == 5) ch = '.';
	if(b == 2 && a == 5) ch = '?';
	if(b == 3 && a == 5) ch = '!';
	if(b == 4 && a == 5) ch = ' ';
      }
      cout << ch;
    }
    cout << endl;
    
  EXIT:;
  }
  
  return 0;
}