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<vector>
#include<map>
#include<string>
using namespace std;
typedef pair < int , int > Pi;
typedef pair < int , Pi > Pii;
#define fr first
#define sc second
const int dy[][4] = {{1,0,-1,0},{0,-1,0,1},{-1,0,1,0},{0,1,0,-1}};
const int dx[][4] = {{0,1,0,-1},{1,0,-1,0},{0,-1,0,1},{-1,0,1,0}};
const int dm[][4] = {{3,0,1,2},{0,1,2,3},{1,2,3,0},{2,3,0,1}};
const int my[] = { 0, -1, 0, 1}, mx[] = { 1, 0, -1, 0};
const int md[] = { 2, 3, 0, 1};
int w, h;
char mas[30][30];
vector< Pii > vc;
string tmp = "ENWS";
int search( int y , int x){
  for(int i = 0 ; i < vc.size() ; i++ ){
    if(Pi(y,x) == vc[i].sc){
      return i;
    }
  }
  return -1;
}
vector< Pii >  solve(){
  //向き変えるじゃん
  vector< Pii > java;
  for(int i = 0 ; i < vc.size() ; i++ ){
    //向きは毎回変えるじゃん(震え声)
    for(int j = 0 ; j < 4 ; j++ ){
      int yy = vc[i].sc.fr + dy[vc[i].fr][j];
      int xx = vc[i].sc.sc + dx[vc[i].fr][j];
      if(mas[yy][xx] != '#' && search(yy,xx) == -1){
        vc[i].fr = dm[vc[i].fr][j];
        break;
      }
    }
  }
  //動けないひとをプッシュしよう
  bool list[1000] = {};
  for(int i = 0 ; i < h ; i++ ){
    for(int j = 0 ; j < w ; j++ ){
      if(mas[i][j] == '#' || search(i,j) != -1) continue;
      for(int k = 0 ; k < 4 ; k++ ){
        int ny = i + my[k], nx = j + mx[k], iti;
        if((iti = search(ny,nx)) == -1) continue;
        if(vc[iti].fr == md[k]){
          if(mas[i][j] != 'X') java.push_back(Pii(vc[iti].fr,Pi(i,j)));
          list[iti] = true;
          break;
        }
      }
    }
  }
  for(int i = 0 ; i < vc.size() ; i++ ){
    if(!list[i]) java.push_back(vc[i]);
  }
  return java;
}
int main(){
  while(cin >> w >> h , w){
    for(int i = 0 ; i < h ; i++ ){
      for(int j = 0 ; j < w ; j++ ){
        cin >> mas[i][j];
        if(tmp.find(mas[i][j]) != string::npos){
          vc.push_back(Pii( tmp.find(mas[i][j]), Pi( i, j)));
        }
      }
    }
    int ret = 0;
    while(ret <= 180 && !vc.empty()){
      vc = solve();
      ret++;
    }
    if(ret == 181) cout << "NA" << endl;
    else cout << ret << endl;
    vc.clear();
  }
}

C++: #include <iostream>
#include <sstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <climits>
#include <cfloat>
using namespace std;


int main()
{
    int dir[256];
    dir['E'] = 0;
    dir['N'] = 1;
    dir['W'] = 2;
    dir['S'] = 3;

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

    int nextDir[] = {3, 0, 1, 2};

    for(;;){
        int w, h;
        cin >> w >> h;
        if(w == 0)
            return 0;

        vector<string> s(h);
        for(int i=0; i<h; ++i)
            cin >> s[i];

        int n = 0;
        vector<int> y, x, d;
        for(int i=0; i<h; ++i){
            for(int j=0; j<w; ++j){
                if('E' <= s[i][j] && s[i][j] <= 'W'){
                    y.push_back(i);
                    x.push_back(j);
                    d.push_back(dir[s[i][j]]);
                    ++ n;
                    s[i][j] = '!';
                }
            }
        }

        int m = n;
        for(int t=1; t<=180; ++t){
            vector<bool> move(n, false);
            for(int i=0; i<n; ++i){
                if(s[y[i]][x[i]] == 'X')
                    continue;
                for(int j=0; j<4; ++j){
                    int d1 = (d[i] + nextDir[j]) % 4;
                    int y1 = y[i] + dy[d1];
                    int x1 = x[i] + dx[d1];
                    if(s[y1][x1] == '.' || s[y1][x1] == 'X'){
                        d[i] = d1;
                        move[i] = true;
                        break;
                    }
                }
            }

            for(int i=0; i<4; ++i){
                for(int j=0; j<n; ++j){
                    if(!move[j] || d[j] != (i+2)%4)
                        continue;
                    int y1 = y[j] + dy[d[j]];
                    int x1 = x[j] + dx[d[j]];
                    if(s[y1][x1] == '.' || s[y1][x1] == 'X'){
                        s[y[j]][x[j]] = '.';
                        if(s[y1][x1] == 'X'){
                            -- m;
                        }else{
                            s[y1][x1] = '!';
                        }
                        y[j] = y1;
                        x[j] = x1;
                    }
                }
            }
            if(m == 0){
                cout << t << endl;
                break;
            }
        }

        if(m != 0)
            cout << "NA" << endl;
    }
}