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,b,n) for(int i=b;i<n;i++)
#define rep(i,n)   REP(i,0,n)
#define E 0
#define N 1
#define W 2
#define S 3

int dx[]={1,0,-1,0};
int dy[]={0,-1,0,1};
int opp[]={W,S,E,N};
char m[30][30];

bool move(int r,int c,int y,int x){
  rep(i,4){
    int nex=x+dx[i],ney=y+dy[i];
    if ( nex<0||ney<0||ney>=r||nex>=c)continue;
    if ( m[ney][nex] == opp[i]){
      m[ney][nex]='.';
      if ( m[y][x] == 'X')return true;
      else {m[y][x]=opp[i]+10;return false;}
    }
  }
  return false;
}

void nextD(int r,int c,int y,int x,int d){
  rep(i,4){
    int now = (d+4+i-1)%4;
    int nex=x+dx[now],ney=y+dy[now];
    if ( nex<0||ney<0||nex>=c||ney>=r)continue;
    if ( m[ney][nex]=='.'||m[ney][nex]=='X'){
      m[y][x]=now;
      return;
    }
  }
}


int solve(int r,int c,int person){
  int time=0;
  while(person && time < 181){
    time++;
    rep(i,r)
      rep(j,c)
      if ( m[i][j]==E||m[i][j]==S||
	   m[i][j]==W||m[i][j]==N)nextD(r,c,i,j,m[i][j]);

    rep(i,r){
      rep(j,c){
	if ( move(r,c,i,j)==true ){
	  person--;
	}
      }
    }

    rep(i,r)
      rep(j,c)if ( m[i][j]>=10 && m[i][j] <=13)m[i][j]-=10;

  }
  if ( person != 0)return -1;
  return time;
}


main(){
  int c,r;
  while(cin>>c>>r && c){
    int cnt = 0;
    rep(i,r){
      cin>>m[i];
      rep(j,c){
	if ( m[i][j]=='E')m[i][j]=E,cnt++;
	else if ( m[i][j] == 'S')m[i][j]=S,cnt++;
	else if ( m[i][j] == 'W')m[i][j]=W,cnt++;
	else if ( m[i][j] == 'N')m[i][j]=N,cnt++;
      }
    }
    int ans = solve(r,c,cnt);
    if ( ans == -1)cout << "NA"<<endl;
    else cout << ans << endl;
  }
  return false;
}

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

int foo(char c) {
	switch(c) {
		case 'N' : return 0;
		case 'E' : return 1;
		case 'S' : return 2;
		case 'W' : return 3;
	}
	return -1;
}

char bar(int n) {
	switch(n) {
		case 0 : return 'N';
		case 1 : return 'E';
		case 2 : return 'S';
		case 3 : return 'W';
	}
	return '@';
}

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

int W, H;
bool valid(int i, int j) {
	return 0 <= i && i < H && 0 <= j && j < W;
}

int main() {
	while(cin >> W >> H, W || H) {
		vector<string> sq;
		for(int i = 0; i < H; i++) {
			string s;
			cin >> s; sq.push_back(s);
		}

		int ret = -1;
		for(int t = 0; t < 180; t++) {
			vector<string> nex;

			/* turn */
			for(int i = 0; i < sq.size(); i++) {
				for(int j = 0; j  < sq[i].size(); j++) {
					if(foo(sq[i][j]) != -1) {
						for(int k = 0; k < 4; k++) {
							int x,y;
							int dir = (k + 4 - foo(sq[i][j])) % 4;
							y = i + dy[dir];
							x = j + dx[dir];
							if(!valid(y, x))
								continue;
							if(sq[y][x] == '.' || sq[y][x] == 'X') {
								sq[i][j] = bar((5 - dir)%4);
								break;
							}
						}
					}
				}
			}

			/* debug 
			if(t < 20) {
				for(int i = 0; i < sq.size(); i++) {
					for(int j = 0; j < sq[i].size(); j++) {
						cout << sq[i][j];
					} cout << endl;
				}
				cout << endl;
			}
			// */

			/* move */
			for(int i = 0; i < 4; i++) {
				/*
				if(t < 20)
					cout << bar((3-i)%4) << endl;
				// */
				for(int j = 0; j < sq.size(); j++) {
					for(int k = 0; k < sq[j].size(); k++) {
						if(sq[j][k] == bar((3-i)%4)) {
							int x, y;
							x = k + dx[(i+2)%4];
							y = j + dy[(i+2)%4];
							if(valid(y,x) && sq[y][x] == '.') {
								sq[y][x] = (int)sq[j][k] - ('A' - 'a');
								sq[j][k] = '@';
							}
							else if(valid(y,x) && sq[y][x] == 'X') {
								sq[y][x] = 'x';
								sq[j][k] = '@';
								ret = t;
							}
						}
					}
				}
			}
			/* debug 
			if(t < 20) {
				for(int i = 0; i < sq.size(); i++) {
					for(int j = 0; j < sq[i].size(); j++) {
						cout << sq[i][j];
					} cout << endl;
				}
				cout << endl;
			}
			// */

			for(int i = 0; i < sq.size(); i++) {
				for(int j = 0; j < sq[i].size(); j++) {
					if(sq[i][j] == '@')
						sq[i][j] = '.';
					else if(sq[i][j] == 'x')
						sq[i][j] = 'X';
					if(sq[i][j] == 'n' || sq[i][j] == 'e' || sq[i][j] == 'w' || sq[i][j] == 's')
						sq[i][j] = (int)sq[i][j] + 'A' - 'a';
				}
			}
		}

		for(int i = 0; i < sq.size(); i++) {
			for(int j = 0; j < sq.size(); j++) {
				if(foo(sq[i][j]) != -1) {
					ret = -1;
				}
			}
		}

		if(ret == -1)
			cout << "NA" << endl;
		else
			cout << ret + 1 << endl;
	}
}