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<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;
				}
				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(from[ny][nx] != 0 && from[ny][nx] != i+1)continue;
					if(from[ny][nx] == i+1){
						stage[ny][nx] = '.';
						player[i].y = memo[i].y;
						player[i].x = memo[i].x;
						player[i].type = memo[i].type;
						if(stage[memo[i].y][memo[i].x] == 'X'){
							del.PB(player[i]);
						}
						else{
							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;
}

C++: #include<iostream>
#include<set>
#include<map>
using namespace std;

typedef pair<int,int> P;

int dir(char a){
  if(a=='E')return 0;
  if(a=='N')return 1;
  if(a=='W')return 2;
  if(a=='S')return 3;
  return -1;
}

char inv_dir(int a){
  if(a==0)return 'E';
  if(a==1)return 'N';
  if(a==2)return 'W';
  return 'S';
}

int main(){
  int h,w;
  string grid[30];
  int dx[] = {1,0,-1,0},dy[] = {0,-1,0,1};

  while(cin >> w >> h && (w||h)){
    for(int i=0;i<h;i++)cin >> grid[i];

    int ans = 0;
    while(ans<=180){
      set<P> s;
      int num=0;
      for(int i=0;i<h;i++){
	for(int j=0;j<w;j++){
	  int d = dir(grid[i][j]);
	  if(0<=d){
	    num++;
	    for(int k=-1;k<3;k++){
	      int dd = (d+k+4)%4;
	      int sy = i+dy[dd], sx = j+dx[dd];
	      if(sy<0 || sx<0 || h<=sy || w<=sx)continue;
	      if(grid[sy][sx] == '.' || grid[sy][sx] == 'X'){
		grid[i][j] = inv_dir(dd);
		s.insert(P(sy,sx));
		break;
	      }
	    }
	  }
	}
      }

      if(!num)break;
      set<P>::iterator ite;
      for(ite=s.begin();ite!=s.end();ite++){
	P p = *ite;
	for(int i=0;i<4;i++){
	  int sy = p.first+dy[i], sx = p.second+dx[i];
	  if(sy<0 || sx<0 || h<=sy || w<=sx)continue;
	  int dd = (i+2)%4;
	  if(dir(grid[sy][sx])==dd){
	    grid[sy][sx] = '.';
	    if(grid[p.first][p.second]!='X')grid[p.first][p.second] = inv_dir(dd);
	    break;
	  }
	}
      }
      ans++;
    }
    if(ans>180)cout << "NA\n";
    else cout << ans << endl;
  }
}