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>
using namespace std;
#define rep(i,n) for(int i = 0 ; i < n ; i++) 

int dx[] = {1,0,-1,0};
int dy[] = {0,-1,0,1};
string dd = "ENWS";
int main(){
	int H,W;
	while(cin >> W >> H && W){
		char c[31][31]={},C[31][31]={};
		for(int i = 0 ; i < H ; i++)
			for(int j = 0 ; j < W ; j++)
				cin >> c[i][j];
		int sec = 0 , ok = 0;
		while(sec <= 180){
			int endok = 1;
			rep(i,H)rep(j,W) if(c[i][j] == 'E' || c[i][j] == 'S' || c[i][j] == 'W' || c[i][j] == 'N') endok = 0;
			if(endok){
				cout << sec << endl;
				ok = true;
				break;
			}
			pair<int,int> next[31][31];
			int done[31][31] = {};
			
			rep(i,31)rep(j,31) next[i][j] = make_pair(-1,-1);
			rep(i,H)rep(j,W) C[i][j] = c[i][j];
			rep(i,31)rep(j,31) if(C[i][j] == 'E' || C[i][j] == 'S' || C[i][j] == 'W' || C[i][j] == 'N') C[i][j] = '.';
			
			rep(i,H)rep(j,W) {
				if(c[i][j] == 'E' || c[i][j] == 'S' || c[i][j] == 'W' || c[i][j] == 'N'){
					int b = (dd.find(c[i][j]) + 3)%4;
					rep(d,4){
						int nx = j + dx[(b+d)%4];
						int ny = i + dy[(b+d)%4];
						if(c[ny][nx] == '.' || c[ny][nx] == 'X'){
							next[i][j]= make_pair(nx,ny);
							break;
						}
					}
				}
			}
			rep(i,H)rep(j,W) {
				if( c[i][j] == '.' || c[i][j] == 'X'){
					rep(d,4){
						int nx = j + dx[d];
						int ny = i + dy[d];
						if( (c[ny][nx] == 'E' || c[ny][nx] == 'S' || c[ny][nx] == 'W' || c[ny][nx] == 'N') && next[ny][nx] == make_pair(j,i)){
							if(done[i][j]){
								C[ny][nx] = dd[(d + 2)%4]; 
							}else{
								if( c[i][j] != 'X' ) {
									//if( sec < 10 ) cout << c[ny][nx] << " " << endl;
									C[i][j] = dd[(d + 2)%4]; 
									done[i][j] = true;
								}
							}
						}
					}
				}
			}
			//if(sec < 10) rep(i,H) cout << C[i] << endl;
			rep(i,H)rep(j,W) c[i][j] = C[i][j];
			sec++;
		}
		if(!ok) cout << "NA" << endl;
	}
}

C++: #include<iostream>
using namespace std;
int dy[]={-1,0,1,0};
int dx[]={0,1,0,-1};
int change(char ch){
  if(ch=='N')return 0;
  if(ch=='E')return 1;
  if(ch=='S')return 2;
  if(ch=='W')return 3;
  return -1;
}
char change2(int x){
  if(x==0)return 'N';
  if(x==1)return 'E';
  if(x==2)return 'S';
  if(x==3)return 'W';
  return '-';
}
char t[30][30];
int W,H;

bool inField(int y,int x){
  if(y<0||x<0)return false;
  if(y>=H||x>=W)return false;
  return true;
}

int main(){
  while(1){
    cin>>W>>H;
    if(W==0&&H==0)break;
    for(int i=0;i<H;i++)
      for(int j=0;j<W;j++)
	cin>>t[i][j];
    int ans=0;
    while(1){
      ///////////////////////////////////////////////
      bool flag=false;
      for(int i=0;i<H;i++){
	for(int j=0;j<W;j++){
	  if(change(t[i][j])==-1)continue;
	  flag=true;
	  int dir=change(t[i][j]);
	  for(int k=5;k>=2;k--){
	    int ndir=(dir+k)%4;
	    int ny=i+dy[ndir],nx=j+dx[ndir];
	    if(!inField(ny,nx))continue;
	    if(t[ny][nx]=='.'||t[ny][nx]=='X'){
	      t[i][j]=change2(ndir);
	      break;
	    }
	  }//k
	}//j
      }//i
      if(flag==false)break;
      ///////////////////////////////////////////////
      ans++;
      if(ans>180)break;
      /////////////////////////////////////////////// w s e n
      bool flg[30][30];
      for(int i=0;i<30;i++)for(int j=0;j<30;j++)flg[i][j]=false;

      for(int k=3;k>=0;k--){
	for(int i=0;i<H;i++){
	  for(int j=0;j<W;j++){
	    if(k!=change(t[i][j]))continue;
	    if(flg[i][j]==true)continue;

	    int ny=i+dy[k],nx=j+dx[k];
	    if(t[ny][nx]=='.'||t[ny][nx]=='X'){
	      if(t[ny][nx]=='.')t[ny][nx]=t[i][j];
	      t[i][j]='.';
	      flg[ny][nx]=true;
	    }	    
	  }
	}
      }
      ///////////////////////////////////////////////
      
    }
    if(ans>180)cout<<"NA"<<endl;
    else cout<<ans<<endl;
  }
  return 0;
}