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 <cstdlib>
#include <string>
#include <vector>
#include <deque>
#include <list>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <cstring>
#include <cctype>
#include <sstream>
#include <set>
#include <map>
#include <queue>
#include <complex>
using namespace std;
#define REP(i,n) for(int i = 0; i < (int)n; i++)
#define FOR(i,a,b) for(int i = a; i < (int)b; i++)
const int INF = 1<<28;
const int MAX_H = 35;
const int MAX_W = 35;

struct P {
  int h, w, d;
  P(int a, int b, int c) {h = a; w = b; d = c;}
  bool operator > (const P& a) const {
    return d > a.d; 
  }
};

int my[] = {0, 1, 0, -1};
int mx[] = {-1, 0, 1, 0};
int W, H;
int field[MAX_H][MAX_W];


int dicideDirection(int &w, int &h, int &d){
  REP(i, 4) {
    if((d+i+3)%4 == 0 && w - 1 >= 0 && field[h][w-1] > 99) return 0;
    else if((d+i+3)%4 == 1 && h + 1 < H && field[h+1][w] > 99) return 1;
    else if((d+i+3)%4 == 2 && w + 1 < W && field[h][w+1] > 99) return 2;
    else if((d+i+3)%4 == 3 && h - 1 >= 0 && field[h-1][w] > 99) return 3;
  }
  return d;
}

int main() {
  while(cin >> W >> H, W|H) {
    REP(i, H) REP(j, W) {
      char in; cin >> in;
      if(in == '#') field[i][j] = 10;
      else if(in == '.') field[i][j] = 100;
      else if(in == 'X') field[i][j] = 1000;
      else if(in == 'E') field[i][j] = 2;
      else if(in == 'N') field[i][j] = 3;
      else if(in == 'W') field[i][j] = 0;
      else if(in == 'S') field[i][j] = 1;
    }

    queue<P> q;
    priority_queue<P, vector<P>, greater<P> > pq;
    REP(i, H) REP(j, W)
      if(field[i][j] < 4)
        q.push(P(i, j, field[i][j]));

    int cnt = 0;
    while(q.size() | pq.size()) {

      //dicide direction
      while(q.size()) {
        P pp = q.front(); q.pop();
        int next_d = dicideDirection(pp.w, pp.h, pp.d);
        pp.d = next_d;
        pq.push(pp);
        field[pp.h][pp.w] = next_d;
      }

      //dicide move
      while(pq.size()) {
        P pp = pq.top(); pq.pop();
        if(pp.d == 0 && field[pp.h][pp.w-1] > 99) {
          if(field[pp.h][pp.w-1] == 1000)
            field[pp.h][pp.w] = 100;
          else {
            swap(field[pp.h][pp.w], field[pp.h][pp.w-1]);
            q.push(P(pp.h, pp.w-1, pp.d));
          }
        }
        else if(pp.d == 1 && field[pp.h+1][pp.w] > 99) {
          if(field[pp.h+1][pp.w] == 1000)
            field[pp.h][pp.w] = 100;
          else {
            swap(field[pp.h][pp.w], field[pp.h+1][pp.w]);
            q.push(P(pp.h+1, pp.w, pp.d));
          }
        }
        else if(pp.d == 2 && field[pp.h][pp.w+1] > 99) {
          if(field[pp.h][pp.w+1] == 1000)
            field[pp.h][pp.w] = 100;
          else {
            swap(field[pp.h][pp.w], field[pp.h][pp.w+1]);
            q.push(P(pp.h, pp.w+1, pp.d));
          }
        }
        else if(pp.d == 3 && field[pp.h-1][pp.w] > 99) {
          if(field[pp.h-1][pp.w] == 1000)
            field[pp.h][pp.w] = 100;
          else {
            swap(field[pp.h][pp.w], field[pp.h-1][pp.w]);
            q.push(P(pp.h-1, pp.w, pp.d));
          }
        }
        else
          q.push(pp);
      }
      cnt++;
      if(cnt > 180) break;
    }
    if(cnt > 180) cout << "NA" << endl;
    else cout << cnt << endl;
  }
  return 0;
}

C++: #include<iostream>
using namespace std;
int dy[]={-1,0,1,0};
int dx[]={0,1,0,-1};
bool isEmpty(char ch){
  if(ch=='.'||ch=='X')return true;
  else return false;
}
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],tmp[30][30];
int W,H,gy[900],gx[900],size;
 
int main(){
  while(1){
    cin>>W>>H;
    if(W==0&&H==0)break;
    size=0;
    for(int i=0;i<H;i++){
      for(int j=0;j<W;j++){
	cin>>t[i][j];
	if(t[i][j]=='X'){
	  gy[size]=i;
	  gx[size]=j;
	  size++;
	}
      }
    }

    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(isEmpty(t[ny][nx])){
	      t[i][j]=change2(ndir);
	      break;
	    }
	  }//k
	}//j
      }//i
      if(flag==false)break;
      ///////////////////////////////////////////////
      ans++;
      if(ans>180)break;
      /////////////////////////////////////////////// w s e n
      
      for(int i=0;i<H;i++){
	for(int j=0;j<W;j++){
	  if(change(t[i][j])==-1){
	    tmp[i][j]=t[i][j];
	  }else tmp[i][j]='.';
	}
      }
      
      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;
	    int ny=i+dy[k],nx=j+dx[k];
	    if(isEmpty(t[ny][nx])&&isEmpty(tmp[ny][nx])){
	      tmp[ny][nx]=t[i][j];
	    }else{
	      tmp[i][j]=t[i][j];
	    }
	  }
	}
      }
      
      for(int i=0;i<H;i++){
	for(int j=0;j<W;j++){
	  t[i][j]=tmp[i][j];
	}
      }

      for(int i=0;i<size;i++){
	t[gy[i]][gx[i]]='X';
      }
      ///////////////////////////////////////////////
      
    }
    if(ans>180)cout<<"NA"<<endl;
    else cout<<ans<<endl;
  }
  return 0;
}