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 <cstdio>
#include <vector>
#include <algorithm>
#include <complex>
#include <queue>
#include <map>
#include <set>
#include <cstring>
#include <cstdlib>
#include <string>
#include <cmath>
using namespace std;

#define REP(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
const int INF = 1<<29;

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

string str = "ENWS";
int main() {
  int w,h;
  while(cin>>w>>h,w||h) {
    char ba[w][h];
    REP(y,h) REP(x,w) cin >> ba[x][y];
    int res = -1;
    REP(time, 180) {
      int man = 0;
      REP(y,h) {
        //cout << endl;
        REP(x,w) {
          REP(i,4) {
            if (ba[x][y] == str[i]) {
              man++;
              REP(k,4) {
                int d = (i+3+k)%4;
                int xx = x+dx[d];
                int yy = y+dy[d];
                if (ba[xx][yy]=='X'||ba[xx][yy]=='.') {
                  ba[x][y] = str[d];
                  goto OUT;
                }
              }
            }
          }
        OUT:;
        }
      }
      char next[w][h];
      memcpy(next, ba, sizeof(ba));
      REP(x,w) {
        REP(y,h) {
          if (ba[x][y] != '.' && ba[x][y] != 'X') continue;
          REP(k,4) {
            int xx = x+dx[k];
            int yy = y+dy[k];
            if (xx<0||xx>=w||yy<0||yy>=h) continue;

            if (ba[xx][yy] == str[(k+2)%4]) {
              if (ba[x][y] == '.')
                next[x][y] = ba[xx][yy];
              else
                man--;
              next[xx][yy] = '.';
              break;
            }
          }
        }
      }
      if (man==0) {
        res = time + 1;
        break;
      }
      memcpy(ba,next,sizeof(next));
    }
    if (res>=0)
      cout << res << endl;
    else
      cout << "NA" << endl;
  }
}

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

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

int main()
{
	int W,H;
	while(cin >> W >> H, (W||H))
	{
		int cnt=0, p[35][35],tp[35][35];
		char f[35][35];
		cin.ignore();
		for(int i=0; i<H; i++)
		{
			string t;
			getline(cin, t);
			for(int j=0; j<W; j++)
			{
				f[j][i]=t[j];
				p[j][i]=-1;
				if(f[j][i]=='E') p[j][i]=0;
				if(f[j][i]=='S') p[j][i]=3;
				if(f[j][i]=='W') p[j][i]=2;
				if(f[j][i]=='N') p[j][i]=1;
				
				if(p[j][i]!=-1) cnt++;
			}
		}
		
		int ret=0;
		for(; ret<=180; ret++)
		{
			if(cnt==0) break;
			
			for(int i=0; i<H; i++)
			for(int j=0; j<W; j++)
			{
				tp[j][i]=-1;
				
				if(p[j][i]!=-1)
				{
					int next=p[j][i];
					for(int k=0; k<4; k++)
					{
						int d=(p[j][i]+k+3)%4;
						int tx=j+dx[d], ty=i+dy[d];
						if(tx<0||ty<0||tx>=W||ty>=H) continue;
						if(f[tx][ty]=='#'||p[tx][ty]!=-1) continue;
						
						next=d;
						break;
					}
					
					p[j][i]=next;
				}
			}
			
			for(int i=0; i<H; i++)
			for(int j=W-1; j>=0; j--)
			{
				if(p[j][i]!=-1)
				{
					int tx=j+dx[p[j][i]], ty=i+dy[p[j][i]];
					if(tp[tx][ty]==-1&&p[tx][ty]==-1) tp[tx][ty]=p[j][i];
					else tp[j][i]=p[j][i];
				}
			}
			
			memcpy(p, tp, sizeof(p));
			
			for(int i=0; i<H; i++)
			for(int j=0; j<W; j++)
			{
				if(f[j][i]=='X'&&p[j][i]!=-1)
				{
					cnt--;
					p[j][i]=-1;
				}
			}
		}
		
		if(ret>180) cout <<"NA"<< endl;
		else cout << ret << endl;
	}
}