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++: #include <cstdio>
#include <vector>
#include <algorithm>
#include <string>
#include <map>
#include <set>
#include <queue>
#include <cstring>

using namespace std;

#define reep(i,f,t) for(int i=f ; i<int(t) ; ++i)
#define rep(i,n) reep(i, 0, n) 

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;

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

int main()
{
	int h, w;
	while(scanf("%d%d", &w, &h), w){
		char field[32][32];
		rep(i, h){
			scanf("%s", field[i]);
		}

		int t;
		for(t=0; t<180; ++t){
			int human = 0;
			rep(i, h) rep(j, w){
				int dir = -1;
				if(field[i][j] == 'E') dir = 0;
				if(field[i][j] == 'N') dir = 1;
				if(field[i][j] == 'W') dir = 2;
				if(field[i][j] == 'S') dir = 3;

				if(dir<0)
					continue;
				++human;

				const int dd[] = {3, 0, 1, 2};
				int newdir = dir;
				rep(k, 4){
					int pd = (dir + dd[k]) % 4;
					int py = i + dy[pd];
					int px = j + dx[pd];
					if(field[py][px] == '.' || field[py][px] == 'X'){
						newdir = pd;
						break;
					}
				}
				field[i][j] = "ENWS"[newdir];
			}
			
			char next[32][32];
			rep(i, h) rep(j, w)
				next[i][j] = field[i][j];
			
			rep(i, h) rep(j, w){
				rep(k, 4){
					if(field[i][j] != '.' && field[i][j] != 'X')
						continue;
					
					int py = i + dy[k];
					int px = j + dx[k];
					if(py<0 || h<=py || px<0 || w<=px)
						continue;
					
					if(field[py][px] == "WSEN"[k]){
						if(field[i][j] == '.'){
							next[i][j] = field[py][px];
						}else
							--human;
						next[py][px] = '.';
						break;
					}
				}
			}
			if(human == 0)
				break;
			rep(i, h) rep(j, w)
				field[i][j] = next[i][j];
		}
		if(t == 180)
			puts("NA");
		else
			printf("%d\n", t+1);
	}

	return 0;
}

C++: #define _USE_MATH_DEFINES
#define INF 10000000
#include <iostream>
#include <sstream>
#include <cmath>
#include <algorithm>
#include <queue>
#include <stack>
#include <limits>
#include <map>
#include <string>
#include <cstring>
#include <set>
#include <deque>
#include <bitset>
#include <list>

using namespace std;

typedef long long ll;
typedef pair<int,int> P;

static const double eps = 1e-8;

struct DATA{
	char dirPrev;
	char dirNext;
	P prev;
	P next;
};

char stage[30][30];

static const int moveTo[][2] = {{1,0},{0,-1},{-1,0},{0,1}};
//static const char dir[] = {'N','W','S','E'};


void changeDir(int W,int H){
	map<char,int> dir;
	dir['N'] = 0; dir['W'] = 1; dir['S'] = 2; dir['E'] = 3;
	const char num2dir[] = {'E','N','W','S'};
	//# Ç
	//.(sIh)°
	//X ñíû
	//E ðü¢Ä¢él
	//N kðü¢Ä¢él
	//W ¼ðü¢Ä¢él
	//S ìðü¢Ä¢él

	for(int y=0;y<H;y++){
		for(int x=0;x<W;x++){
			switch(stage[y][x]){
			case '#':			  
				break;
			case 'X':
				break;
			case 'N': case 'W': case 'S': case 'E':
				for(int i=0;i<4;i++){
					int dx = x + moveTo[(i+dir[stage[y][x]])%4][0];
					int dy = y + moveTo[(i+dir[stage[y][x]])%4][1];
					if(dy < 0 || dy >= H || dx < 0 || dx >= W) continue;
					if(stage[dy][dx] == '.' || stage[dy][dx] == 'X'){
						stage[y][x] = num2dir[(i+dir[stage[y][x]])%4];
						break;
					}
				}

				break;
			default :
				break;
			}

		}
	}
}

void movePlayer(int W,int H){
	map<char,int> dir;
	dir['N'] = 0; dir['W'] = 1; dir['S'] = 2; dir['E'] = 3;
	const char num2other_dir[] = {'W','S','E','N'};
	//# Ç
	//.(sIh)°
	//X ñíû
	//E ðü¢Ä¢él
	//N kðü¢Ä¢él
	//W ¼ðü¢Ä¢él
	//S ìðü¢Ä¢él

	bool used[30][30];
	fill((bool*)used,(bool*)used+30*30,false);
	for(int dy=0;dy<H;dy++){
		for(int dx=0;dx<W;dx++){
			
			switch(stage[dy][dx]){
			case '#':			  
				break;
			case 'X':
				for(int i=0;i<4;i++){
					int sx = dx + moveTo[i][0];
					int sy = dy + moveTo[i][1];
					
					if(sy < 0 || sy >= H || sx < 0 || sx >= W) continue;
					if(used[sy][sx]) continue;
					if(stage[sy][sx] == num2other_dir[i]){
						stage[sy][sx] = '.';
						used[dy][dx] = true;
						break;
					}
				}
				break;
			case '.':
				for(int i=0;i<4;i++){
					int sx = dx + moveTo[i][0];
					int sy = dy + moveTo[i][1];
					
					if(sy < 0 || sy >= H || sx < 0 || sx >= W) continue;
					if(used[sy][sx]) continue;
					if(stage[sy][sx] == num2other_dir[i]){
						stage[dy][dx] = num2other_dir[i];
						stage[sy][sx] = '.'; 
						used[dy][dx] = true;
						break;
					}
				}
				break;
			case 'N': case 'W': case 'S': case 'E':
				break;
			default :
				break;
			}

		}
	}
}

void printStage(int W,int H){
	for(int y=0;y<H;y++){
		for(int x=0;x<W;x++){
			printf("%c",stage[y][x]);
		}
		printf("\n");
	}
}

bool isClear(int W,int H){
	for(int y=0;y<H;y++){
		for(int x=0;x<W;x++){
			switch(stage[y][x]){
			case 'N': case 'W': case 'S': case 'E':
				return false;
				break;
			default:
				break;
			}
		}
	}
	return true;
}

int main(){
	int W,H;
	while(~scanf("%d %d",&W,&H)){
		if(W==H && H==0) break;
		for(int y=0;y<H;y++){
			char buf[32];
			scanf("%s",buf);
			for(int x=0;x<W;x++){
				stage[y][x] = buf[x];
			}
		}

		int res=0;
		while(!isClear(W,H)){
			//printStage(W,H);
			changeDir(W,H);
			movePlayer(W,H);
			res++;
			if(res > 180) break;
		}

		if(res > 180) printf("NA\n");
		else printf("%d\n",res);

	}

}