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<vector>
#include<string>
#include<algorithm>
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<cstdio>
#include<sstream>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mp make_pair
#define all(in) in.begin(),in.end()
const double PI=acos(-1);
const double EPS=1e-8;
const int inf=1e9;
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;
int main(){
	int dx[]={0,-1,0,1,0,-1,0,1};
	int dy[]={1,0,-1,0,1,0,-1,0};
	int n,m;
	while(cin>>m>>n,n+m){
		vector<string>in(n);
		rep(i,n)cin>>in[i];
		rep(i,n)rep(j,m)if(in[i][j]=='N')in[i][j]='0';
		else if(in[i][j]=='E')in[i][j]='3';
		else if(in[i][j]=='S')in[i][j]='2';
		else if(in[i][j]=='W')in[i][j]='1';
		int c=0;
		rep(i,n)rep(j,m)if(isdigit(in[i][j]))c++;
		rep(q,181){
			if(q==180){
				cout<<"NA"<<endl;
				break;
			}
			vector<string>tmp=in;
			rep(i,n)rep(j,m)if(isdigit(tmp[i][j]))tmp[i][j]='.';
			rep(i,n)for(int j=m-1;j>=0;j--)if(isdigit(in[i][j])){
				int t=in[i][j]-'0';
				rep(k,4)if(in[i+dx[t+k]][j+dy[t+k]]!='#'&&
					!isdigit(in[i+dx[t+k]][j+dy[t+k]])){
					//if(!isdigit(tmp[i+dx[t+k]][j+dy[t+k]]))
					if(in[i+dx[t+k]][j+dy[t+k]]=='X'){
						c--;
						if(c==0){
							cout<<q+1<<endl;
							goto end;
						}
					}else if(!isdigit(tmp[i+dx[t+k]][j+dy[t+k]]))
						tmp[i+dx[t+k]][j+dy[t+k]]=(in[i][j]-'0'+k+3)%4+'0';
					else tmp[i][j]=in[i][j];
					break;
				}
			}
			in=tmp;
//			rep(i,n)cout<<in[i]<<endl;cout<<endl;
		}
		end:;
	}
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
#include<cmath>
#include<cassert>
#include<map>
#include<queue>
#define REP(i,s,n) for(int i=s;i<n;i++)
#define rep(i,n) REP(i,0,n)
#define inf (1<<28)
#define MAX 35
#define next(a,b) ((((a+3)%4)+b)%4)
using namespace std;

struct P
{
  int x,y,dir;
  P(int x=inf,int y=inf,int dir=inf):x(x),y(y),dir(dir){}
};

int dx[] = {+1,+0,-1,+0};
int dy[] = {+0,-1,+0,+1};
int H,W;
char G[MAX][MAX];
int  I[MAX][MAX];
int  D[MAX][MAX];
int  Next[MAX][MAX];
string DIR = "ENWS";
vector<P> vec;

bool Finish()
{
  rep(i,vec.size())
    {
      if(G[vec[i].y][vec[i].x] != 'X')return false;
    }
  return true;
}

void print()
{
  cout << "print- ---" << endl;
  rep(i,H)
    {
      rep(j,W)
	{
	  cout << G[i][j];
	}
      cout << endl;
    }
  cout << endl;
}
void print2()
{
  cout << "2print- ---" << endl;
  rep(i,H)
    {
      rep(j,W)
	{
	  cout << D[i][j];
	}
      cout << endl;
    }
  cout << endl;
}

void decide()
{
  rep(i,vec.size())
    {
      int x = vec[i].x;
      int y = vec[i].y;
      if(G[y][x] == 'X')continue;
      int dir = vec[i].dir;
      rep(j,4)
	{
	  int nx = x + dx[next(dir,j)];
	  int ny = y + dy[next(dir,j)];
	  if(!(0 <= nx && nx < W && 0 <= ny && ny < H))continue;
	  if(!(G[ny][nx] == '.' || G[ny][nx] == 'X'))continue;
	  Next[y][x] = next(dir,j);
	  D[ny][nx]++;
	  break;
	}
    }
}

bool check(int x,int y,int cx,int cy)
{
  rep(i,4)
    {
      int nx = cx + dx[i];
      int ny = cy + dy[i];
      if(!(0 <= nx && nx < W && 0 <= ny && ny < H))continue;
      if(G[ny][nx] == '.' || G[ny][nx] == 'X' || G[ny][nx] == '#')continue;
      return nx == x && ny == y;
    }
  assert(false);
}

void move()
{
  rep(i,vec.size())
    {
      int x = vec[i].x;
      int y = vec[i].y;
      if(G[y][x] == 'X')continue;
      int dir = vec[i].dir;
   
      int nx = x + dx[Next[y][x]];
      int ny = y + dy[Next[y][x]];
      if(!(0 <= nx && nx < W && 0 <= ny && ny < H))continue;
      if(!(G[ny][nx] == '.' || G[ny][nx] == 'X'))continue;
      if(D[ny][nx] == 0)
	{
	  cout << i << " is out: " << x << "," << y << " -> " << nx << "," << ny << endl; 
	  print();
	  print2();
	}
      if(D[ny][nx] == 0)continue;
      //assert(D[ny][nx]);
      if(D[ny][nx] == 1 || (D[ny][nx] >= 2 && check(x,y,nx,ny)))
	{
	  G[y][x] = '.';
	  vec[i].x = nx, vec[i].y = ny, vec[i].dir = Next[y][x];
	  if(G[ny][nx] != 'X')G[ny][nx] = DIR[Next[y][x]];
	}

    }
  rep(i,H)rep(j,W)D[i][j] = 0;
}

int main()
{
  while(cin >> W >> H,W|H)
    {
      vec.clear();
      rep(i,H)rep(j,W)
	{
	  cin >> G[i][j];
	  I[i][j] = -inf;
	  if(!(G[i][j] == '.' || G[i][j] == '#' || G[i][j] == 'X'))
	    {
	      char c = G[i][j];
	      int dir = (c=='E'?0:(c=='N'?1:(c=='W'?2:(c=='S'?3:-inf))));
	      vec.push_back(P(j,i,dir));

	    }
	}


      if(vec.empty())
	{
	  cout << 0 << endl;
	  continue;
	}

      rep(phase,180)
	{
	  // print();
	  decide();

	  move();

	  if(Finish())
	    {
	      cout << phase+1 << endl;
	      goto Fin;
	    }
	}
      cout << "NA" << endl;
    Fin:;
    }

  return 0;
}