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 <stdio.h>
#include <sstream>
#include <string>
#include <vector>
#include <map>
#include <queue>
#include <algorithm>
#include <set>
#include <math.h>
#include <utility>
#include <stack>
#include <string.h>
#include <complex>
using namespace std;
const int INF = 1<<29;

typedef complex<int> P;
const P turn[] = {P(0,1),P(1,0),P(0,-1),P(-1,0)};
const int dx[] = {1,0,-1,0};
const int dy[] = {0,1,0,-1};

struct person{
    P pos,dire;
    bool active,not_move;
};

int pos2i[30][30];
char field[30][30];
int w,h;

int pos_rank(P& dire){
    if(dire==turn[3]) return 0;
    else if(dire==turn[0]) return 1;
    else if(dire==turn[1]) return 2;
    else return 3;
}

int main(){
    while(1){
        scanf("%d%d",&w,&h);
        if(w==0)break;

        vector<person> people;
        for(int i=0;i<h;i++){
            for(int j=0;j<w;j++){
                cin >> field[i][j];
                if(field[i][j]=='S'){
                    people.push_back((person){P(j,i),turn[0],true,false});
                }else if(field[i][j]=='E'){
                    people.push_back((person){P(j,i),turn[1],true,false});
                }else if(field[i][j]=='N'){
                    people.push_back((person){P(j,i),turn[2],true,false});
                }else if(field[i][j]=='W'){
                    people.push_back((person){P(j,i),turn[3],true,false});
                }
            }
        }

        int t = 0, goal_num = 0;
        while(goal_num<people.size()&&t<=180){
            t++;
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    pos2i[i][j] = -1;
                }
            }
            for(int i=0;i<people.size();i++){
                if(people[i].active) pos2i[imag(people[i].pos)][real(people[i].pos)] = i;
            }

            for(int i=0;i<people.size();i++){
                person& p = people[i];
                if(!p.active) continue;
                for(int j=0;j<4;j++){
                    P next_pos = p.pos + p.dire * turn[j];
                    int nextx = real(next_pos), nexty = imag(next_pos);
                    if(0<=nextx && nextx<w && 0<=nexty && nexty<h){
                        if(pos2i[nexty][nextx]==-1 && field[nexty][nextx]!='#'){
                            p.dire *= turn[j];
                            break;
                        }
                    }
                }
            }

            for(int i=0;i<people.size();i++)people[i].not_move = false;
            for(int i=0;i<people.size();i++){
                if(!people[i].active || people[i].not_move) continue;
                P pi_next_pos = people[i].pos + people[i].dire;
                int nextx = real(pi_next_pos), nexty = imag(pi_next_pos);
                if(field[nexty][nextx]=='#' || pos2i[nexty][nextx]>=0) continue;

                for(int j=i+1;j<people.size();j++){
                    if(!people[j].active || people[i].not_move) continue;
                    P pj_next_pos = people[j].pos + people[j].dire;
                    if(pi_next_pos == pj_next_pos){
                        int rank_i = pos_rank(people[i].dire),rank_j = pos_rank(people[j].dire);
                        if(rank_i < rank_j){
                            people[j].not_move = true;
                        }else{
                            people[i].not_move = true;
                            break;
                        }
                    }
                }
                if(!people[i].not_move){
                    people[i].pos = pi_next_pos;
                    if(field[imag(pi_next_pos)][real(pi_next_pos)]=='X'){
                        people[i].active = false;
                        goal_num++;
                    }
                }
            }
        }
        if(t<=180) printf("%d\n",t);
        else printf("NA\n");

        //break;
    }

    return 0;
}