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>
using namespace std;

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

int main()
{
  int W, H;
  while (cin >> W >> H) {
    if ((W|H) == 0)
      break;

    vector<string> maze(H);
    for (int i = 0; i < H; ++i) {
      cin >> maze[i];
      for (int j = 0; j < W; ++j) {
	if (maze[i][j] == 'E')
	  maze[i][j] = '0';
	else if (maze[i][j] == 'N')
	  maze[i][j] = '1';
	else if (maze[i][j] == 'W')
	  maze[i][j] = '2';
	else if (maze[i][j] == 'S')
	  maze[i][j] = '3';
      }
    }

    int ans = -1;
    for (int t = 1; t <= 181; ++t) {
      // change dir
      for (int i = 0; i < H; ++i) {
	for (int j = 0; j < W; ++j) {
	  if (maze[i][j] == 'X' || maze[i][j] == '.' || maze[i][j] == '#')
	    continue;

	  bool change = false;
	  int dir = maze[i][j] - '0', next_dir;
	  for (int d = 0; d < 4; ++d) {
	    next_dir = (dir+d+3) % 4;
	    int x = j + dx[next_dir];
	    int y = i + dy[next_dir];
	    if (x < 0 || W <= x || y < 0 || H <= y ||
		maze[y][x] != '.' && maze[y][x] != 'X')
	      continue;
	    change = true;
	    break;
	  }

	  if (change)
	    maze[i][j] = static_cast<char>(next_dir + '0');
	}
      }

      vector<string> cpy = maze;
      // move
      for (int i = 0; i < H; ++i) {
	for (int j = 0; j < W; ++j) {
	  if (maze[i][j] != 'X' && maze[i][j] != '.')
	    continue;

	  for (int d = 0; d < 4; ++d) {
	    int x = j + dx[d];
	    int y = i + dy[d];
	    
	    if (x < 0 || W <= x || y < 0 || H <= y ||
		maze[y][x] == '#' || maze[y][x] == 'X' || maze[y][x] == '.')
	      continue;

	    int dir = maze[y][x] - '0';
	    int xx = x+dx[dir], yy = y+dy[dir];
	    if (j != xx || i != yy)
	      continue;
	    
	    if (maze[i][j] == 'X') {
	      cpy[y][x] = '.';
	      maze[y][x] = '#';
	    } else {
	      cpy[i][j] = maze[y][x];
	      cpy[y][x] = '.';
	      maze[i][j] = maze[y][x] = '#';
	    }
	    ans = t;
	    break;
	  }
	}
      }

      maze = cpy;
    }

    if (ans == 181)
      cout << "NA" << endl;
    else
      cout << ans << endl;
  }
  return 0;
}