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 <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pll> pip;
const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-9;

int dx[4] = {1,0,-1,0}, dy[4] = {0,1,0,-1};
int dd[4] = {1,0,3,2}; // ???, ???, ???, ???

int W, H;
int maps[30][30];
bool wait[30][30][4]; // (i,j)???k??????????????????

int main() {
	while (cin >> W >> H, W || H) {
		queue<pii> que;
		
		REP(i, H) {
			string str; cin >> str;
			
			REP(j, W) {
				int num;
				switch (str[j]) {
					case '#': num = -1; break;
					case '.': num = -2; break;
					case 'X': num = -3; break;
					
					case 'E': num = 0; break;
					case 'S': num = 1; break;
					case 'W': num = 2; break;
					case 'N': num = 3; break;
				}
				maps[i][j] = num;
				if (num >= 0) que.push(pii(i, j));
			}
		}
		
		int turn = 0;
		
		while (turn <= 180 && !que.empty()) {
			//puts(""); REP(i, H) {REP(j, W) printf("%3d", maps[i][j]); puts("");}
			
			for (int i = que.size() - 1; i >= 0; i--) {
				pii now = que.front(); que.pop();
				int y = now.fi, x = now.se;
				int d = maps[y][x];
				
				int nextd = -1;
				
				REP(i, 4) {
					int nd = (d + dd[i]) % 4;
					int xx = x + dx[nd], yy = y + dy[nd];
					if (!(xx >= 0 && xx < W && yy >= 0 && yy < H)) continue;
					if (maps[yy][xx] < 0 && maps[yy][xx] != -1) {
						wait[yy][xx][(nd + 2) % 4] = true;
						nextd = nd;
						
						//printf("%d %d -> %d %d (%d)\n", y, x, yy, xx, nd);
						break;
					}
				}
				
				if (nextd == -1) que.push(pii(y, x));
			}
			
			REP(i, H) REP(j, W) {
				bool ok = false;
				REP(k, 4) {
					int d = dd[(k + 1) % 4];
					if (!wait[i][j][d]) continue;
					int y = i + dy[d], x = j + dx[d];
					maps[y][x] = (d + 2) % 4;
					
					if (ok) que.push(pii(y, x));
					else {
						if (maps[i][j] != -3) {
							swap(maps[y][x], maps[i][j]);
							que.push(pii(i, j));
						}
						else maps[y][x] = -2;
						ok = true;
					}
					wait[i][j][d] = false;
				}
				
			}
			
			turn++;
		}
		
		if (turn > 180) puts("NA");
		else cout << turn << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <sstream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cassert>

using namespace std;

#define FOR(i,k,n) for(int i=(k); i<(int)(n); ++i)
#define REP(i,n) FOR(i,0,n)
#define FORIT(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)

template<class T> void debug(T begin, T end){ for(T i = begin; i != end; ++i) cerr<<*i<<" "; cerr<<endl; }
inline bool valid(int x, int y, int W, int H){ return (x >= 0 && y >= 0 && x < W && y < H); }

typedef long long ll;
const int INF = 100000000;
const double EPS = 1e-8;
const int MOD = 1000000007;
int dx[4] = {1, 0, -1, 0}; //→↑←↓
int dy[4] = {0, -1, 0, 1};

int main(){
  int W, H;
  while(cin>>W>>H && W){
    vector<string> grid(H);
    REP(i, H) cin >> grid[i];
    REP(y, H) REP(x, W) if(grid[y][x] == 'X') grid[y][x] = '&';
    const string NWSE = "NWSE"; // ↑←↓→
    REP(time, 182){
      bool gameover = true;
      REP(y, H)REP(x, W) if(isupper(grid[y][x])){
        gameover = false;
        int sr = -1;
        REP(i, 4) if(NWSE[i] == grid[y][x]) sr = i;
        assert(sr != -1);
        REP(dr, 4){
          int r = (sr + dr) % 4;
          int nx = x + dx[r];
          int ny = y + dy[r];
          if(valid(nx, ny, W, H) && (grid[ny][nx] == '.' || grid[ny][nx] == '&')){
            grid[y][x] = NWSE[(r + 3) % 4];
            break;
          }
        }
      }
      if(time >= 181){
        cout << "NA" << endl;
        break;
      }
      if(gameover){
        cout << time << endl;
        break;
      }
      int dx2[4] = {-1, 0, 1, 0};
      int dy2[4] = {0, 1, 0, -1}; //←↓→↑
      bool used[30][30] = {};
      const string WSEN = "WSEN"; //←↓→↑
      REP(y, H)REP(x, W)REP(i, 4) if(grid[y][x] == WSEN[i] && !used[y][x]){
        used[y][x] = true;
        int nx = x + dx2[i];
        int ny = y + dy2[i];
        if(valid(nx, ny, W, H) && !used[ny][nx]){
          if(grid[ny][nx] == '.'){
            grid[ny][nx] = grid[y][x];
            grid[y][x] = '.';
          }else if(grid[ny][nx] == '&'){
            used[ny][nx] = true;
            grid[y][x] = '.';
          }
        }
      }
      /*
      cout << "time: " << time << endl;
      REP(y, H){
        cout << grid[y] << endl;
      }
      cout << endl;
      */
    }
  }

  return 0;
}