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;

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

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 main() {
	int W, H;
	while(cin >> W >> H, W|H) {
		int field[H][W];
		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();
//				cout << pp.h << ' ' << pp.w << ' ' << pp.d << ' ' << cnt << endl;
				bool flg = true;
				REP(i, 4) {
					int nd = (pp.d + 3 + i) % 4;
					int nh = pp.h + dy[nd], nw = pp.w + dx[nd];
					if(0 <= nh && 0 <= nw && nh < H && nw < W  && field[nh][nw] > 99) {
						pp.d = nd; pq.push(pp);
						field[pp.h][pp.w] = nd;
						flg = false;
						break;
					}
				}
				if(flg) pq.push(pp);
			}

			//dicide move
			while(pq.size()) {
				P pp = pq.top(); pq.pop();
				int nh = pp.h + dy[pp.d], nw = pp.w + dx[pp.d];
				if(field[nh][nw] > 99) {
					if(field[nh][nw] == 1000)
						field[pp.h][pp.w] = 100;
					else {
						swap(field[pp.h][pp.w], field[nh][nw]);
						q.push(P(nh, nw, pp.d));
					}
				}
				else
					q.push(pp);
			}
			cnt++;
			if(cnt > 181) break;
		}
		if(cnt > 181) cout << "NA" << endl;
		else cout << cnt << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <cstdlib>

using namespace std;

const int N = 30;

int h, w, p;
char mapData[N][N];
char next[N][N];
int dy[] = {0, -1, 0, 1};
int dx[] = {1, 0, -1, 0};

int convertDirection(char c){
   if(c == 'E') return 0;
   if(c == 'N') return 1;
   if(c == 'W') return 2;
   if(c == 'S') return 3;
}

char convertInteger(int d){
   if(d == 0) return 'E';
   if(d == 1) return 'N';
   if(d == 2) return 'W';
   if(d == 3) return 'S';
}

void changeDirection(int y, int x, char c){
   for(int i=0;i<4;++i){
      int d = (convertDirection(c)+3+i)%4;
      int ty = y + dy[d];
      int tx = x + dx[d];
      if(ty<0 || ty>=h) continue;
      if(tx<0 || tx>=w) continue;
      if(mapData[ty][tx] == '.' || mapData[ty][tx] == 'X'){
         mapData[y][x] = convertInteger(d);
         return;
      }
   }
}

void searchPerson(){
   for(int i=0;i<h;++i){
      for(int j=0;j<w;++j){
         if(mapData[i][j] == 'E' || 
            mapData[i][j] == 'N' || 
            mapData[i][j] == 'W' ||
            mapData[i][j] == 'S')
            changeDirection(i, j, mapData[i][j]);
      }
   }
}

void copy(){
   for(int i=0;i<h;++i){
      for(int j=0;j<w;++j){
         mapData[i][j] = next[i][j];
      }
   }
}
void movePerson(int y, int x, int ty, int tx){
   if(mapData[y][x] == 'X'){
      --p;
   }else{
      next[y][x] = mapData[ty][tx];
   }
   next[ty][tx] = '.';
}

void selectPerson(int y, int x){
   for(int i=0;i<4;++i){
      int ty = y + dy[i];
      int tx = x + dx[i];
      if(ty<0 || ty>=h) continue;
      if(tx<0 || tx>=w) continue;
      if(mapData[ty][tx] == '#' || mapData[ty][tx] == '.' || mapData[ty][tx] == 'X') continue;
      if(convertDirection(mapData[ty][tx]) == (i+2)%4){
         movePerson(y, x, ty, tx);
         break;
      }
   }
}

void searchPoint(){
   for(int i=0;i<h;++i){
      for(int j=0;j<w;++j){
         if(mapData[i][j] == '.' || mapData[i][j] == 'X')
            selectPerson(i, j);
      }
   }
   copy();
}

main(){
   while(cin >> w >> h && (h || w)){
      p = 0;
      for(int i=0;i<h;++i){
         for(int j=0;j<w;++j){
            cin >> mapData[i][j];
            if(mapData[i][j] == 'E' || 
               mapData[i][j] == 'N' || 
               mapData[i][j] == 'W' ||
               mapData[i][j] == 'S')
               ++p;
         }
      }
      if(p == 0){
         cout << 0 << endl;
         continue;
      }
      for(int i=0;i<h;++i){
         for(int j=0;j<w;++j){
            next[i][j] = mapData[i][j];
         }
      }
      for(int t=1;;++t){
         if(t > 180){
            cout << "NA" << endl;
            break;
         }
         searchPerson();
         searchPoint();
         if(p == 0){
            cout << t << endl;
            break;
         }
      }
   }
   return 0;
}