Go: package main

import (
	"bufio"
	"os"
	"strconv"
	"strings"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

type Point struct {
	x, y int
}

func main() {
	dx := []int{1, 0, -1, 0}
	dy := []int{0, -1, 0, 1}
	maze := make([][]rune, 30)
	for i := range maze {
		maze[i] = make([]rune, 30)
	}
	next := make([][]rune, 30)
	for i := range next {
		next[i] = make([]rune, 30)
	}
	check := make([][]int, 30)
	for i := range check {
		check[i] = make([]int, 30)
	}
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		W, _ := strconv.Atoi(buf[0])
		H, _ := strconv.Atoi(buf[1])
		if W == 0 && H == 0 {
			break
		}
		for i := 0; i < H; i++ {
			scanner.Scan()
			buf_ := scanner.Text()
			for j, v := range buf_ {
				maze[i][j] = v
			}
		}
		man := 0
		for i := 0; i < H; i++ {
			for j := 0; j < H; j++ {
				if maze[i][j] != '.' && maze[i][j] != 'X' && maze[i][j] != '#' {
					switch maze[i][j] {
					case 'E':
						maze[i][j] = 0
						man++
					case 'N':
						maze[i][j] = 1
						man++
					case 'W':
						maze[i][j] = 2
						man++
					case 'S':
						maze[i][j] = 3
						man++
					}
				}
			}
		}
		ans := -1
		for t := 0; t <= 180; t++ {
			if man == 0 {
				ans = t
				break
			}
			for i := 0; i < H; i++ {
				for j := 0; j < W; j++ {
					check[i][j] = 0x7FFFFFFF
				}
			}
			for i := 0; i < H; i++ {
				for j := 0; j < W; j++ {
					if maze[i][j] > 3 {
						continue
					}
					l := (maze[i][j] + 3) % 4
					for k := 0; k < 4; k++ {
						y := i + dy[l]
						x := j + dx[l]
						if 0 <= y && y < H && 0 <= x && x < W && (maze[y][x] == '.' || maze[y][x] == 'X') {
							maze[i][j] = l
							check[y][x] = min(check[y][x], int((l+2)%4))
							break
						}
						l = (l + 1) % 4
					}
				}
			}
			for i := 0; i < H; i++ {
				for j := 0; j < W; j++ {
					next[i][j] = maze[i][j]
				}
			}
			for i := 0; i < H; i++ {
				for j := 0; j < W; j++ {
					if maze[i][j] > 3 {
						continue
					}
					y := i + dy[maze[i][j]]
					x := j + dx[maze[i][j]]
					if 0 <= y && y < H && 0 <= x && x < W && check[y][x] == int((maze[i][j]+2)%4) {
						if maze[y][x] == '.' {
							next[y][x] = maze[i][j]
						} else if maze[y][x] == 'X' {
							man--
						}
						next[i][j] = '.'
					}
				}
			}
			for i := 0; i < H; i++ {
				for j := 0; j < W; j++ {
					maze[i][j]=next[i][j]
				}
			}
		}
		if ^ans != 0 {
			fmt.Println(ans)
		} else {
			fmt.Println("NA")
		}
	}
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

C++: #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;
}