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 <map>
#include <cstdlib>
#include <algorithm>
#include <string>

using namespace std;

const int N = 30;

int h, w, t, p;
char data[N][N], next[N][N];
int dy[] = {0, -1, 0, 1};
int dx[] = {1, 0, -1, 0};
map<char, int> ctoi;
string itoc = "ENWS";

void copy(){
   for(int i=0;i<h;++i){
      for(int j=0;j<w;++j){
         data[i][j] = next[i][j];
      }
   }
}

main(){
   ctoi['E'] = 0;
   ctoi['N'] = 1;
   ctoi['W'] = 2;
   ctoi['S'] = 3;
   while(cin >> w >> h && (h || w)){
      p = 0;
      for(int i=0;i<h;++i){
         for(int j=0;j<w;++j){
            cin >> next[i][j];
            if(next[i][j] == 'E' ||
               next[i][j] == 'N' ||
               next[i][j] == 'W' ||
               next[i][j] == 'S') ++p;
         }
      }
      copy();
      for(t=0;t<=180;++t){
         //if(p == 0) break;
         int sum = 0;
         for(int i=0;i<h;++i){
            for(int j=0;j<w;++j){
               if(data[i][j] == 'E' ||
                  data[i][j] == 'N' ||
                  data[i][j] == 'W' ||
                  data[i][j] == 'S') ++sum;
            }
         }
         if(sum == 0) break;
         for(int i=0;i<h;++i){
            for(int j=0;j<w;++j){
               if(data[i][j] == '#' ||
                  data[i][j] == '.' ||
                  data[i][j] == 'X') continue;
               for(int k=0;k<4;++k){
                  int d = (ctoi[data[i][j]] + 3 + k) % 4;
                  int ty = i + dy[d];
                  int tx = j + dx[d];
                  if(ty<0 || ty>=h) continue;
                  if(tx<0 || tx>=w) continue;
                  if(data[ty][tx] == '.' || data[ty][tx] == 'X'){
                     data[i][j] = itoc[d];
                     break;
                  }
               }
            }
         }
         for(int i=0;i<h;++i){
            for(int j=0;j<w;++j){
               //if(data[i][j] == '.' || data[i][j] == 'X'){
               if(data[i][j] != '#'){
                  for(int k=0;k<4;++k){
                     int ty = i + dy[k];
                     int tx = j + dx[k];
                     if(ty<0 || ty>=h) continue;
                     if(tx<0 || tx>=w) continue;
                     if(data[ty][tx] == '#' ||
                        data[ty][tx] == '.' ||
                        data[ty][tx] == 'X') continue;
                        if(abs(ctoi[data[ty][tx]] - k) == 2){
                        if(data[i][j] == 'X') --p;
                        else next[i][j] = data[ty][tx];
                        next[ty][tx] = '.';
                        break;
                     }
                  }
               }
            }
         }
         copy();
      }
      if(t > 180) cout << "NA" << endl;
      else cout << t << endl;
   }
   return 0;
}

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

int main() {

  int dx[4] = { 1, 0, -1, 0 };
  int dy[4] = { 0, -1, 0, 1 };

  while( true ) {

    int w,h;

    cin >> w >> h;

    if ( w == 0 ) break;

    int m[32][32] = {0};

    char input;

    int cnt = 0;

    for ( int i = 0; i < h + 2; i++ ) {

      for ( int j = 0; j < w + 2; j++ ) {

	if ( i == 0 || i == h+1 || j == 0 || j == w+1 ) {

	  m[j][i] = 1;
	  continue;

	}

	cin >> input;

	if ( input == '#' ) {
	  m[j][i] = 1;
	}else if ( input == '.' ) {
	  m[j][i] = 0;
	}else if ( input == 'X' ) {
	  m[j][i] = 2;
	}else if ( input == 'E' ) {
	  m[j][i] = 3;
	  cnt++;
	}else if ( input == 'N' ) {
	  m[j][i] = 4;
	  cnt++;
	}else if ( input == 'W' ) {
	  m[j][i] = 5;
	  cnt++;
	}else if ( input == 'S' ) {
	  m[j][i] = 6;
	  cnt++;
	}

      }

    }

    int t = 0;

    while( true ) {

      t++;
      if ( t > 180 ) {
	cout << "NA" << endl;
	break;
      }

      for ( int i = 1; i < h + 1; i++ ) {

	for ( int j = 1; j < w + 1; j++ ) {

	  if ( m[j][i] >= 3 ) {

	    for ( int l = 0; l < 4; l++ ) {

	      int k = ( ( m[j][i] + l ) % 4 );
	      if ( m[ j+dx[k] ][ i+dy[k] ] == 0 || m[ j+dx[k] ][ i+dy[k] ] == 2 ) {

		m[j][i] = k + 3;
		break;

	      }

	    }

	  }

	}

      }

      int c[32][32] = {0};

      while( true ) {

	bool flag = true;

      for ( int i = 1; i < h + 1; i++ ) {

	for ( int j = 1; j < w + 1; j++ ) {

	  if ( m[j][i] == 0 || m[j][i] == 2 ) {

	    for ( int l = 0; l < 4; l++ ) {

	      if ( m[ j+dx[l] ][ i+dy[l] ] >= 3 ) {

		if ( c[ j+dx[l] ][ i+dy[l] ] == 1 ) continue;
		if ( ( ( m[ j+dx[l] ][ i+dy[l] ] - l ) % 4 ) == 1 ) {

		  if ( m[j][i] == 0 ) {
		    m[j][i] = m[ j+dx[l] ][ i+dy[l] ];
		  }else {
		    cnt--;
		  }
		  m[ j+dx[l] ][ i+dy[l] ] = 0;
		  c[j][i] = 1;
		  flag = false;
		  break;

		}

	      }

	    }

	  }

	}

      }

      if ( flag == true ) break;

      }

      if ( cnt == 0 ) {
	cout << t << endl;
	break;
      }

      /*
      if ( t < 10 ) {
	for ( int i = 1; i < h + 1; i++ ) {

	  for ( int j = 1; j < w + 1; j++ ) {

	    cout << m[j][i];

	  }

	  cout << endl;

	}

      }
      */

    }

  }

  return 0;

}