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>
using namespace std;

#define REP(i,n) for(int i=0;i<(int)(n);++i)

int R, C;
string table[32];
int num[32][32];

const int dr[] = {0, -1, 0, 1};
const int dc[] = {1, 0, -1, 0};

const string aim = "ENWS";
inline int isPerson(int ch) {
  if( ch == 'E' ) return 0;
  if( ch == 'N' ) return 1;
  if( ch == 'W' ) return 2;
  if( ch == 'S' ) return 3;
  return -1;
}

int solve() {
  for(int turn = 0; turn < 180; turn++) {
    REP(i, R) REP(j, C) num[i][j] = 0;
    int o = 0;
    REP(r, R) REP(c, C) {
      if( isPerson( table[r][c] ) >= 0 ) {
        o++;
        int d = isPerson(table[r][c]);
        for(int k = 0; k < 4; k++) {
          int nr = r + dr[(k + d + 3) % 4];
          int nc = c + dc[(k + d + 3) % 4];
          if( table[nr][nc] == '.' || table[nr][nc] == 'X' ) {
            d = (k + d + 3) % 4;
            ++num[nr][nc];
            break;
          }
        }
        table[r][c] = aim[d];
      }
    }
    if( o == 0 ) return turn;

//     REP(i, R) cout << table[i] << endl;
//     cout << endl;

    REP(r, R) REP(c, C) {
      if( num[r][c] > 0 ) {
        REP(k, 4) {
          int nr = r + dr[k];
          int nc = c + dc[k];
          if( 0 <= nr && nr < R && 0 <= nc && nc < C && isPerson( table[nr][nc] ) >= 0 ) {
            int d = isPerson( table[nr][nc] );
            if( nr + dr[d] != r || nc + dc[d] != c ) continue;
            if( table[r][c] == 'X' ) {
              table[nr][nc] = '.';
            } else {
              swap( table[r][c], table[nr][nc] );
            }
            break;
          }
        }
      }
    }

  }
  return -1;
}
int main() {
  for(;;) {
    cin >> C >> R; if( R == 0 && C == 0 ) break;
    REP(i, R) cin >> table[i];

    int res = solve();
    if( res == -1 ) cout << "NA" << endl;
    else cout << res << endl;
  }
  return 0;
}

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

using namespace std;

const int max_size = 30;

void p(char a[max_size][max_size], int sizei, int sizej = 0, int offseti = 0, int offsetj = 0){
	if(!sizej) sizej = sizei;
	for(int i = 0; i < sizei; i++){
		for(int j = 0; j < sizej; j++){
			cout << a[offseti+i][offsetj+j] << ' ';
		}
		cout << endl;
	}
}

char dirchr[] = "ENWS";
int dx[] = {1, 0, -1, 0};
int dy[] = {0, -1, 0, 1};

int dirnum(char d){
	for(int i = 0; i < 4; i++){
		if(dirchr[i] == d) return i;
	}
	cout << "invalid char" << d << endl;
	exit(0);
}

void changeDirection(char (*_map)[max_size], int i, int j){
	int startdir = dirnum(_map[i][j]) + 3; // 現在の向きの右から
	for(int k = 0; k < 4; k++){
		int dir = (startdir+k)%4;
		if(_map[i+dy[dir]][j+dx[dir]] == '.' || _map[i+dy[dir]][j+dx[dir]] == 'X'){
			//cout << "(" << i << ", " << j << "): " << _map[i][j] << "->" << dirchr[dir] << endl;
			_map[i][j] = dirchr[dir];
			return;
		}
	}
}

void move(char (*_map)[max_size], int i, int j){
	int dir = dirnum(_map[i][j]);
	char destchar = _map[i+dy[dir]][j+dx[dir]];
	if(destchar == '.'){
		_map[i+dy[dir]][j+dx[dir]] = _map[i][j];
		_map[i][j] = '.';
	}
	if(destchar == 'X'){
		_map[i][j] = '.';
	}
}

void peopleAct(char (*_map)[max_size], int i, int j, void (*func)(char (*)[max_size],int, int), char* filter = "ENWS", int filtersize = 4){
	for(int k = 0; k < filtersize; k++){
		if(_map[i][j] == filter[k]){
			(*func)(_map, i, j);
			break;
		}
	}
}

int main(){
	char square[max_size][max_size];

	int w, h;
	while(cin >> w >> h){
		if(!w && !h) break;
		for(int i = 0; i < h; i++){
			for(int j = 0; j < w; j++){
				cin >> square[i][j];
			}
		}
		int time = 0;
		while(time++ <= 180){
			// 向きを変える処理

			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					peopleAct(square, i, j, changeDirection);
					//for(int k = 0; k < 4; k++){
					//	if(square[i][j] == dirchr[k]){
					//		changeDirection(square, i, j);
					//		break;
					//	}
					//}
				}
			}

			// 移動する処理
			// 左、下、右、上の順に処理

			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){ // 左から
					peopleAct(square, i, j, move, "W", 1);
				}
			}

			for(int i = h-1; i >= 0; i--){ // 下から
				for(int j = 0; j < w; j++){
					peopleAct(square, i, j, move, "S", 1);
				}
			}

			for(int i = 0; i < h; i++){
				for(int j = w-1; j >= 0; j-- ){ // 右から
					peopleAct(square, i, j, move, "E", 1);
				}
			}

			for(int i = 0; i < h; i++){ // 上から
				for(int j = 0; j < w; j++){
					peopleAct(square, i, j, move, "N", 1);
				}
			}

			// 人がいなければ避難終了
			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					char c = square[i][j];
					if(c != '.' && c != '#' && c != 'X'){
						goto nextloop;
					}
				}
			}
			break;

nextloop: ;
			//p(square, h, w);
			//getchar();
		}

		//p(square, h, w);

		if(time <= 180){
			cout << time << endl;
		}else{
			cout << "NA" << endl;
		}
	}

	return 0;
}