#define _USE_MATH_DEFINES
#include <iostream>
#include <complex>
#include <algorithm>
#include <vector>
#include <stack>
#include <string>
#include <queue>
#include <cmath>
#include <math.h>
#include <numeric>
#include <list>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <climits>
#include <set>
#include <memory.h>
#include <memory>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cassert>
#include <map>
#include <cassert>
#include <time.h>
#include <ctime>

using namespace std;

typedef complex<double> xy_t;
typedef pair<xy_t, xy_t> line;
typedef long long ll;
typedef pair<int, int> P;
typedef pair<int , P> PP;
typedef pair<int, string> Ps;
typedef vector<int> vec;
typedef vector<vec> mat;
const int INF = 1 << 27;
const double EPS = 1e-10;
const double PI = 3.1415926535897932384626433832795;
const int CLK = CLOCKS_PER_SEC;

#define rep(i, n) for(int i = 0; i < n; i++)
#define rep2(i, m, n) for(int i = m; i < n; i++)
#define repD(i, n) for(int i = n; i >= 0; i--)

char dir[] = {'E', 'N', 'W', 'S'};
int dx[] = {1, 0, -1, 0};
int dy[] = {0, -1, 0, 1};
int w, h, cnt;
char field[32][32];
P pos[1000];
bool goal[1000];
int dr[1000];
int npos[32][32][4];

int main(){
	while(cin >> w >> h && (w || h)){
		fill(&field[0][0], &field[31][31] + 1, '#');
		memset(goal, false, sizeof(goal));
		cnt = 0;
		rep(i,h)rep(j, w){
			cin >> field[i+1][j+1];
			if(field[i+1][j+1] == 'N'){
				pos[cnt] = P(i+1, j+1);
				dr[cnt] = 1;
				cnt++;
			}else if(field[i+1][j+1] == 'E'){
				pos[cnt] = P(i+1, j+1);
				dr[cnt] = 0;
				cnt++;
			}else if(field[i+1][j+1] == 'S'){
				pos[cnt] = P(i+1, j+1);
				dr[cnt] = 3;
				cnt++;
			}else if(field[i+1][j+1] == 'W'){
				pos[cnt] = P(i+1, j+1);
				dr[cnt] = 2;
				cnt++;
			}
		}

		int n = cnt;
		int res = -1;
		rep(t, 181){
			if(cnt ==0){
				res = t;
				break;
			}
			
		//	cout << pos[0].second << " " << pos[0].first << " " << field[pos[0].first][pos[0].second] << endl;
			//@ûüÏX@Ú®óâIÑ
			memset(npos, -1, sizeof(npos));
			rep(i, n){
				if(goal[i]) continue;
				int d = 1;
				rep(j, 4){
					int to = (dr[i] + j + 3) % 4;
					int x2 = pos[i].second + dx[to];
					int y2 = pos[i].first + dy[to];
					if(field[y2][x2] == '.' || field[y2][x2] == 'X'){
						d = j;
						break;
					}
				}

				dr[i] = (dr[i] + d + 3) % 4;
				field[pos[i].first][pos[i].second] = dir[dr[i]];
				int x2 = pos[i].second + dx[dr[i]];
				int y2 = pos[i].first + dy[dr[i]];
				if(field[y2][x2] == '.' || field[y2][x2] == 'X'){
					npos[y2][x2][(dr[i] + 2) % 4] = i;
					
				}
			}

			// Ú®
			rep(i, h){
				rep(j, w){
					if(field[i+1][j+1] == '.'){
						int change = -1;
						rep(k, 4){
							if(npos[i+1][j+1][k] != -1) {
								change = k;
								break;
							}
						}
						if(change >= 0){
							int id = npos[i+1][j+1][change];
							int x = pos[id].second;
							int y = pos[id].first;
							swap(field[i+1][j+1], field[y][x]);
							pos[id] = P(i+1, j+1);
							
						}
					}else if(field[i+1][j+1] == 'X'){
						int change = -1;
						rep(k, 4) {
							if(npos[i+1][j+1][k] != -1){
								change = k;
								break;
							}
						}
						if(change >= 0){
							int id = npos[i+1][j+1][change];
							goal[id] = true;
							field[pos[id].first][pos[id].second] = '.';
							cnt--;
						}
					}
				}
			}
		}
		if(res == -1) cout << "NA" << endl;
		else cout << res << endl;
		
	}
	return 0;
}

Measured memory_bytes: 0