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>

using namespace std;

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

string mp[40];
string next[40];

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

int main() {
  int w, h, dir;
  for (;;) {
    cin >> w >> h;
    if (w == 0 && h == 0) break;
    rep (i, h) cin >> mp[i];
    rep (time, 180) {
      //rep (i, h) cout << mp[i] << endl;
      //cout << endl;
      rep (i, h) rep (j, w) {
	if (mp[i][j] == 'N') {
	  dir = 0;
	} else if (mp[i][j] == 'W') {
	  dir = 1;
	} else if (mp[i][j] == 'S') {
	  dir = 2;
	} else if (mp[i][j] == 'E') {
	  dir = 3;
	} else {
	  continue;
	}
	rep (k, 4) {
	  if (mp[i + dy[(dir + k) % 4]][j + dx[(dir + k) % 4]] == '.'
	      || mp[i + dy[(dir + k) % 4]][j + dx[(dir + k) % 4]] == 'X') {
	    mp[i][j] = "ENWS"[(dir + k) % 4];
	    break;
	  }
	}
      }
      rep (i, h) next[i] = mp[i];
      rep (i, h) rep (j, w) {
	if (mp[i][j] == '.') {
	  if (mp[i][j + 1] == 'W') {
	    next[i][j] = 'W';
	    next[i][j + 1] = '.';
	    continue;
	  }
	  if (mp[i - 1][j] == 'S') {
	    next[i][j] = 'S';
	    next[i - 1][j] = '.';
	    continue;
	  }
	  if (mp[i][j - 1] == 'E') {
	    next[i][j] = 'E';
	    next[i][j - 1] = '.';
	    continue;
	  }
	  if (mp[i + 1][j] == 'N') {
	    next[i][j] = 'N';
	    next[i + 1][j] = '.';
	    continue;
	  }
	}
	if (mp[i][j] == 'X') {
	  if (j < w - 1 && mp[i][j + 1] == 'W') {
	    next[i][j + 1] = '.';
	    continue;
	  }
	  if (0 < i && mp[i - 1][j] == 'S') {
	    next[i - 1][j] = '.';
	    continue;
	  }
	  if (0 < j && mp[i][j - 1] == 'E') {
	    next[i][j - 1] = '.';
	    continue;
	  }
	  if (i < h - 1 && mp[i + 1][j] == 'N') {
	    next[i + 1][j] = '.';
	    continue;
	  }
	}
      }
      rep (i, h) mp[i] = next[i];
      bool end = true;
      rep (i, h) rep (j, w) {
	if (mp[i][j] == 'N') end = false;
	if (mp[i][j] == 'S') end = false;
	if (mp[i][j] == 'W') end = false;
	if (mp[i][j] == 'E') end = false;
      }
      if (end) {
	cout << time + 1 << endl;
	goto aaa;
      }
    }
    cout << "NA\n";
  aaa:;
  }
}

C++: #include<cstdio>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<cstring>
#include<cctype>
#include<complex>
#include<iostream>
#include<sstream>
#include<algorithm>
#include<functional>
#include<vector>
#include<string>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<bitset>
using namespace std;

const int dx[] = {1,0,-1,0};
const int dy[] = {0,-1,0,1};
#define INF 1e+8
#define EPS 1e-10
#define PB push_back
#define fi first
#define se second
#define ll long long 
#define reps(i,j,k) for(int i = (j); i < (k); i++)
#define rep(i,j) reps(i,0,j)
typedef pair<int,int> Pii;
typedef vector<int> vi;
class Data{
	public:
	int y;
	int x;
	int type;
	Data(){}
	Data(int _y,int _x,int _type){
		y = _y;
		x = _x;
		type = _type;
	}
	bool operator==(const Data &a)const{
		return (y == a.y && x == a.x);
	}
};
int chenge(char info){
	if(info == 'E')return 0;
	if(info == 'N')return 1;
	if(info == 'W')return 2;
	if(info == 'S')return 3;
}
bool check(char info){
	if(info != '#' && info != 'X' && info != '.')return true;
	return false;
}
int main(){
	int w,h;
	while(scanf("%d%d",&w,&h),w){
		char stage[32][32]={{0}};
		vector < Data > player;
		rep(i,h){
			scanf("%s",stage[i]);
			rep(j,w){
				if(check(stage[i][j])){
					player.PB(Data(i,j,chenge(stage[i][j])));
				}
			}
		}

		int cnt = 0;
		while(player.size() > 0){
			/*
			rep(i,h){
				printf("%s\n",stage[i]);
			}
			printf("type:%d\n",player[0].type);
			puts("-------------------");
			*/
			cnt++;
			if(cnt >= 180){
				cnt = -1;
				break;
			}
			int len = player.size();
			bool next[32][32]={{false}};
			int from[32][32]={{0}};
			vector < Data > memo;
			vector < Data > del;
			rep(i,len){
				Data d = player[i];
				rep(j,4){
					int k = (d.type+j+3)%4;
					int nx = d.x + dx[k];
					int ny = d.y + dy[k];
					if(ny < 0 || ny > h-1 || nx < 0 || nx > w-1)continue;
					if(stage[ny][nx] == '.' || stage[ny][nx] == 'X'){
						memo.PB(Data(ny,nx,k));
						next[ny][nx] = true;
						from[d.y][d.x] = i+1;
						break;
					}
				}
			}
			rep(i,memo.size()){
				if(!next[memo[i].y][memo[i].x]){
					player[i].type = memo[i].type;
					continue;
				}
				int cnt = 0;
				rep(j,4){
					int ny = memo[i].y+dy[j];
					int nx = memo[i].x+dx[j];
					if(ny < 0 || ny > h-1 || nx < 0 || nx > w-1)continue;
					if(check(stage[ny][nx]) && from[ny][nx] == i+1){
						stage[ny][nx] = '.';
						if(stage[memo[i].y][memo[i].x] == 'X'){
							del.PB(Data(ny,nx,memo[i].type));
						}
						else{
							player[i].y = memo[i].y;
							player[i].x = memo[i].x;
							player[i].type = memo[i].type;
							stage[player[i].y][player[i].x] = memo[i].type+48;
						}
						next[memo[i].y][memo[i].x] = false;
						break;
					}
				}
			}
			rep(i,del.size()){
				vector<Data>::iterator it = remove(player.begin(),player.end(),del[i]);
				player.erase(it,player.end());
			}
		}
		if(cnt == -1)puts("NA");
		else printf("%d\n",cnt);
	}
	return 0;
}