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 <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <iterator>

#define REP(i,k,n) for(int i=k;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)

using namespace std;

string s[30];
int h,w;
int dx[4] = {1,0,-1,0},dy[4] = {0,1,0,-1};

pair<int,int> NextPoint(int y,int x)
{
	pair<int,int> p;
	if(s[y][x] == 'E')
	{
		if(s[y+1][x] == '.' || s[y+1][x] == 'X')
		{
			s[y][x] = 'S';

			p.first = y+1;
			p.second = x;
			return p;
		}
		else if(s[y][x+1] == '.' || s[y][x+1] == 'X')
		{
			s[y][x] = 'E';

			p.first = y;
			p.second = x+1;
			return p;
		}
		else if(s[y-1][x] == '.' || s[y-1][x] == 'X')
		{
			s[y][x] = 'N';

			p.first = y-1;
			p.second = x;
			return p;
		}
		else if(s[y][x-1] == '.' || s[y][x-1] == 'X')
		{
			s[y][x] = 'W';

			p.first = y;
			p.second = x-1;
			return p;
		}
	}
	else if(s[y][x] == 'N')
	{
		if(s[y][x+1] == '.' || s[y][x+1] == 'X')
		{
			s[y][x] = 'E';

			p.first = y;
			p.second = x+1;
			return p;
		}
		else if(s[y-1][x] == '.' || s[y-1][x] == 'X')
		{
			s[y][x] = 'N';

			p.first = y-1;
			p.second = x;
			return p;
		}
		else if(s[y][x-1] == '.' || s[y][x-1] == 'X')
		{
			s[y][x] = 'W';

			p.first = y;
			p.second = x-1;
			return p;
		}
		else if(s[y+1][x] == '.' || s[y+1][x] == 'X')
		{
			s[y][x] = 'S';

			p.first = y+1;
			p.second = x;
			return p;
		}
	}
	else if(s[y][x] == 'W')
	{
		if(s[y-1][x] == '.' || s[y-1][x] == 'X')
		{
			s[y][x] = 'N';

			p.first = y-1;
			p.second = x;
			return p;
		}
		else if(s[y][x-1] == '.' || s[y][x-1] == 'X')
		{
			s[y][x] = 'W';

			p.first = y;
			p.second = x-1;
			return p;
		}
		else if(s[y+1][x] == '.' || s[y+1][x] == 'X')
		{
			s[y][x] = 'S';

			p.first = y+1;
			p.second = x;
			return p;
		}
		else if(s[y][x+1] == '.' || s[y][x+1] == 'X')
		{
			s[y][x] = 'E';

			p.first = y;
			p.second = x+1;
			return p;
		}
	}
	else if(s[y][x] == 'S')
	{
		if(s[y][x-1] == '.' || s[y][x-1] == 'X')
		{
			s[y][x] = 'W';

			p.first = y;
			p.second = x-1;
			return p;
		}
		else if(s[y+1][x] == '.' || s[y+1][x] == 'X')
		{
			s[y][x] = 'S';

			p.first = y+1;
			p.second = x;
			return p;
		}
		else if(s[y][x+1] == '.' || s[y][x+1] == 'X')
		{
			s[y][x] = 'E';
			p.first = y;
			p.second = x+1;
			return p;
		}
		else if(s[y-1][x] == '.' || s[y-1][x] == 'X')
		{
			s[y][x] = 'N';

			p.first = y-1;
			p.second = x;
			return p;
		}
	}
}

bool can(int y,int x)
{
	if(0 <= y & y < h && 0 <= x && x < w)
	{
		return true;
	}
	else return false;
}

bool isPerson(int y,int x)
{
	if(s[y][x] == 'E' || s[y][x] == 'W' || s[y][x] == 'S' || s[y][x] == 'N')
	{
		return true;
	}
	else return false;
}

bool onPerson(int h,int w)
{
	bool flag = false;

	rep(i,h)
	{
		rep(j,w)
		{
			if(s[i][j] == 'E' || s[i][j] == 'N' || s[i][j] == 'W' || s[i][j] == 'S')
			{
				flag = true;
			}
		}
	}

	return flag;
}

void printS(int h,int w)
{
	rep(i,h)
	{
		rep(j,w)
		{
			cout << s[i][j];
		}
		cout << endl;
	}
}

int main()
{
	map<pair<int,int>,int> cmp;

	cmp[pair<int,int>(0,1)] = 1;
	cmp[pair<int,int>(-1,0)] = 2;
	cmp[pair<int,int>(0,-1)] = 3;
	cmp[pair<int,int>(1,0)] = 4;


	while(cin >> w >> h)
	{
		if(w == 0 && h == 0) break;

		rep(i,h)
		{
			cin >> s[i];
		}

		if(!onPerson(h,w))
		{
			cout << 0 << endl;
			return 0;
		}


		bool flag = false;

		rep(k,180)
		{
			vector<pair<int,int> > v;
			map<pair<int,int>,vector<pair<int,int> > > ma;
			rep(i,h) 
			{
				rep(j,w) 
				{	
					if(isPerson(i,j)) 
					{
						//v.push_back(NextPoint(i,j));
						ma[NextPoint(i,j)].push_back(make_pair(i,j));
					}
				}
			}
			

			bool used[30][30];
			rep(i,h) rep(j,w) used[i][j] = true;

			map<pair<int,int>,vector<pair<int,int> > >::iterator ite;
			for(ite = ma.begin();ite != ma.end();ite++)
			{
				int nowy = ite->first.first;
				int nowx = ite->first.second;

				rep(j,ite->second.size())
				{
					int ny = (ite->second)[j].first;
					int nx = (ite->second)[j].second;
				
					if(cmp[pair<int,int>(ny-nowy,nx-nowx)] == 1 && used[nowy][nowx] && used[ny][nx])
					{
						if(s[nowy][nowx] == 'X')
						{
							s[ny][nx] = '.';
						}
						else swap(s[ny][nx],s[nowy][nowx]);

						used[nowy][nowx] = false;
						used[ny][nx] = false;
					}
				}

				rep(j,ite->second.size())
				{
					int ny = (ite->second)[j].first;
					int nx = (ite->second)[j].second;

					if(cmp[pair<int,int>(ny-nowy,nx-nowx)] == 2 && used[nowy][nowx] && used[ny][nx])
					{
						if(s[nowy][nowx] == 'X')
						{
							s[ny][nx] = '.';
						}
						else swap(s[ny][nx],s[nowy][nowx]);

						used[nowy][nowx] = false;
						used[ny][nx] = false;
					}
				}
				rep(j,ite->second.size())
				{
					int ny = (ite->second)[j].first;
					int nx = (ite->second)[j].second;

					if(cmp[pair<int,int>(ny-nowy,nx-nowx)] == 3 && used[nowy][nowx] && used[ny][nx])
					{
						if(s[nowy][nowx] == 'X') s[ny][nx] = '.';
						else swap(s[ny][nx],s[nowy][nowx]);

						used[ny][nx] = false;
						used[nowy][nowx] = false;
					}
				}

				rep(j,ite->second.size())
				{
					int ny = (ite->second)[j].first;
					int nx = (ite->second)[j].second;

					if(cmp[pair<int,int>(ny-nowy,nx-nowx)] == 4 && used[nowy][nowx] && used[ny][nx])
					{
						
						if(s[nowy][nowx] == 'X')
						{
							s[ny][nx] = '.';
						}
						else swap(s[ny][nx],s[nowy][nowx]);

						used[nowy][nowx] = false;
						used[ny][nx] = false;
					}
				}
			}

			if(!onPerson(h,w))
			{
				cout << k+1 << endl;
				flag = true;
				break;
			}
		}

		if(!flag) cout << "NA" << endl;

	}
	return 0;
}