#include <iostream>
#include <complex>
#include <sstream>
#include <string>
#include <algorithm>
#include <deque>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <vector>
#include <set>
#include <limits>
#include <cstdio>
#include <cctype>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <ctime>
using namespace std;
#define REP(i, j) for(int i = 0; i < (int)(j); ++i)
#define FOR(i, j, k) for(int i = (int)(j); i < (int)(k); ++i)
#define SORT(v) sort((v).begin(), (v).end())
#define REVERSE(v) reverse((v).begin(), (v).end())
typedef pair<int, int> P;
const int L = 4;

int W, H;
int my[] = {0, -1, 0, 1};
int mx[] = {1, 0, -1, 0};
map<char, int> ctoi;

class C{
  public:
    int y, x, d, f, g;
    C(){ f = true; }
    C(int yy, int xx, int dd) { y = yy; x = xx; d = dd; f = true; g = false; }
    P front() { return P(y + my[d], x + mx[d]); }
    void move() { y = y + my[d]; x = x + mx[d]; }
};

bool isPerson(int y, int x, vector<string> &v) { return (v[y][x] != '#' && v[y][x] != '.' && v[y][x] != 'X'); }

bool canMoveBeforeTurn(int tar, vector<string> &v, vector<C> &ps){
  P next = ps[tar].front();
  if(v[next.first][next.second] != '.' && v[next.first][next.second] != 'X') return false;
  REP(i, ps.size()) if(i != tar && ps[i].f && next == P(ps[i].y, ps[i].x)) return false;
  return true;
}

bool check(int tar, int n, vector<C> &ps){
  vector<int> v(4);
  v[0] = 2; v[1] = 3; v[2] = 0; v[3] = 1;
  return (v[tar] < v[n]);
}

bool canMoveAfterTurn(int tar, vector<C> &ps){
  REP(i, ps.size()){
    if(!ps[i].f || tar == i) continue;
    if(ps[i].front() == ps[tar].front() && !check(ps[tar].d, ps[i].d, ps)) return false;
  }
  return true;
}

bool isEnd(vector<C> &ps){
  REP(i, ps.size()) if(ps[i].f) return false;
  return true;
}

void disp(vector<string> &v, vector<C> &ps){
  vector<string> vv = v;
  REP(i, ps.size()){
    if(!ps[i].f) continue;
    if(ps[i].d == 0) vv[ps[i].y][ps[i].x] = 'E';
    if(ps[i].d == 1) vv[ps[i].y][ps[i].x] = 'N';
    if(ps[i].d == 2) vv[ps[i].y][ps[i].x] = 'W';
    if(ps[i].d == 3) vv[ps[i].y][ps[i].x] = 'S';
  }
  cout <<endl;
  REP(i, v.size()) cout <<vv[i] <<endl;
}

int main() {
  ctoi['E'] = 0; ctoi['N'] = 1; ctoi['W'] = 2; ctoi['S'] = 3;
  while(cin >>W >>H && W && H){
    vector<string> v(H);
    REP(i, H) cin >>v[i];
    vector<C> ps;
    REP(i, H) REP(j, W) if(isPerson(i, j, v)) { ps.push_back(C(i, j, ctoi[v[i][j]])); v[i][j] = '.'; }

    int res = 0;
    while(!isEnd(ps) && res++ < 180){
      //disp(v, ps);
      REP(i, ps.size()){
        if(!ps[i].f) continue;
        int nds[] = {(ps[i].d + 3) % L, ps[i].d, (ps[i].d + 1) % L, (ps[i].d + 2) % L};
        for(int nd : nds){
          ps[i].d = nd;
          if(canMoveBeforeTurn(i, v, ps)) break;
        }
      }
      REP(i, ps.size()) if(ps[i].f && canMoveAfterTurn(i, ps)) ps[i].g = 1;
      REP(i, ps.size()){
        if(!ps[i].f || ps[i].g == 0) continue;
        ps[i].g = 0;
        ps[i].move();
        if(v[ps[i].y][ps[i].x] == 'X') ps[i].f = false;
      }
    }
    if(res > 180) cout <<"NA" <<endl;
    else cout <<res <<endl;
  }
  return 0;
}