#include <iostream>
#include <sstream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cassert>

using namespace std;

#define FOR(i,k,n) for(int i=(k); i<(int)(n); ++i)
#define REP(i,n) FOR(i,0,n)
#define FORIT(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)

template<class T> void debug(T begin, T end){ for(T i = begin; i != end; ++i) cerr<<*i<<" "; cerr<<endl; }
inline bool valid(int x, int y, int W, int H){ return (x >= 0 && y >= 0 && x < W && y < H); }

typedef long long ll;
const int INF = 100000000;
const double EPS = 1e-8;
const int MOD = 1000000007;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, -1, 0, 1};

int main(){
  int W, H;
  while(cin>>W>>H && W){
    vector<string> grid(H);
    REP(i, H) cin >> grid[i];
    REP(y, H) REP(x, W) if(grid[y][x] == 'X') grid[y][x] = '&';
    const string NWSE = "NWSE";
    const string WSEN = "WSEN";
    REP(time, 182){
      bool gameover = true;
      REP(y, H)REP(x, W) if(isupper(grid[y][x])){
        gameover = false;
        int sr = -1;
        REP(i, 4) if(NWSE[i] == grid[y][x]) sr = i;
        REP(dr, 4){
          int r = (sr + dr) % 4;
          int nx = x + dx[r];
          int ny = y + dy[r];
          if(valid(nx, ny, W, H) && (grid[ny][nx] == '.' || grid[ny][nx] == '&')){
            grid[y][x] = NWSE[(r + 3) % 4];
            break;
          }
        }
      }
      if(time >= 181){
        cout << "NA" << endl;
        break;
      }
      if(gameover){
        cout << time << endl;
        break;
      }
      int dx2[4] = {-1, 0, 1, 0};
      int dy2[4] = {0, 1, 0, -1};
      bool used[30][30] = {};
      REP(y, H)REP(x, W)REP(i, 4) if(grid[y][x] == WSEN[i] && !used[y][x]){
        int nx = x + dx2[i];
        int ny = y + dy2[i];
        if(valid(nx, ny, W, H) && !used[ny][nx]){
          if(grid[ny][nx] == '.'){
            used[ny][nx] = true;
            grid[ny][nx] = grid[y][x];
            grid[y][x] = '.';
          }else if(grid[ny][nx] == '&'){
            used[ny][nx] = true;
            grid[y][x] = '.';
          }
        }
      }
      /*
      cout << "time: " << time << endl;
      REP(y, H){
        cout << grid[y] << endl;
      }
      cout << endl;
      */
    }
  }

  return 0;
}