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 <cmath>
#include <vector>
#include <map>
#include <stack>
#include <queue>
#include <algorithm>
#include <set>
#include <cstring>

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,j) FOR(i,0,j)
#define mp std::make_pair

typedef long long ll;
typedef unsigned long long ull;
typedef std::pair<int,int> P;
typedef std::pair<int,P> State;

const int INF = 1001001001;

// S N E W(南北東西)
const int dx[8] = {0, 0, 1, -1, 1, 1, -1, -1}, dy[8] = {1, -1, 0, 0, 1, -1, 1, -1};

int W, H;
std::string map[30];
std::vector<State> ps;
std::vector<int> rs;
int candicates[30][30];
int order[16] = {3, 0, 2, 1, 2, 1, 3, 0, 0, 2, 1, 3, 1, 3, 0, 2}, 
    order2[4] = {3, 1, 0, 2};

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

int main(){
    while(std::cin >> W >> H, W || H){
        ps.clear();

        REP(i, H){
            std::cin >> map[i];
        
            REP(j, W){
                int d;
                if((d = directionId(map[i][j])) != -1){
                    ps.push_back(mp(d, mp(j, i)));
                    map[i][j] = '#';
                }
            }
        }

        int t = 0;
        while(t <= 180 && !ps.empty()){
            memset(candicates, -1, sizeof(candicates));

            REP(i, (int)ps.size()){
                int d = ps[i].first;
                REP(j, 4){
                    int nx = ps[i].second.first + dx[order[d*4+j]],
                        ny = ps[i].second.second + dy[order[d*4+j]];

                    if(0 <= nx && nx < W &&
                       0 <= ny && ny < H && map[ny][nx] != '#'){
                        ps[i].first = order[d*4+j];
                        // printf("%d, %d, %d, %d: %d\n", i, j, nx, ny, (order[d*4+j]+2)%4);
                        if(candicates[ny][nx] == -1 || (order2[order[d*4+j]]+2) % 4 < candicates[ny][nx] % 4){
                            candicates[ny][nx] = (order2[order[d*4+j]]+2) % 4 + i * 4;
                        }
                        break;
                    }
                }
            }

            REP(i, H){
                REP(j, W){
                    // printf("%d ", candicates[i][j]);
                    if(candicates[i][j] == -1){continue;}

                    int index = candicates[i][j] / 4;
                    map[ps[index].second.second][ps[index].second.first] = '.';
                    if(map[i][j] == 'X'){
                        rs.push_back(index);
                    }else{
                        map[i][j] = '#';
                        ps[index].second = mp(j, i);
                    }
                }
                // puts("");
            }

            std::sort(rs.rbegin(), rs.rend());
            for(auto r : rs){
                ps.erase(ps.begin() + r);
            }
            rs.clear();

            // REP(i, H){
            //     REP(j, W){
            //         putchar(map[i][j]);
            //     }
            //     puts("");
            // }
            // puts("-----------------------------------------");

            t += 1;
        }

        if(t > 180){
            puts("NA");
        }else{
            printf("%d\n", t);
        }
    }

    return 0;
}

C++: #include <iostream>
using namespace std;
#define rep(i,n) for(int i = 0 ; i < n ; i++) 

int dx[] = {1,0,-1,0};
int dy[] = {0,-1,0,1};
string dd = "ENWS";
int main(){
	int H,W;
	while(cin >> W >> H && W){
		char c[31][31]={},C[31][31]={};
		for(int i = 0 ; i < H ; i++)
			for(int j = 0 ; j < W ; j++)
				cin >> c[i][j];
		int sec = 0 , ok = 0;
		while(sec <= 180){
			int endok = 1;
			rep(i,H)rep(j,W) if(c[i][j] == 'E' || c[i][j] == 'S' || c[i][j] == 'W' || c[i][j] == 'N') endok = 0;
			if(endok){
				cout << sec << endl;
				ok = true;
				break;
			}
			pair<int,int> next[31][31];
			int done[31][31] = {};
			
			rep(i,31)rep(j,31) next[i][j] = make_pair(-1,-1);
			rep(i,H)rep(j,W) C[i][j] = c[i][j];
			rep(i,31)rep(j,31) if(C[i][j] == 'E' || C[i][j] == 'S' || C[i][j] == 'W' || C[i][j] == 'N') C[i][j] = '.';
			
			rep(i,H)rep(j,W) {
				if(c[i][j] == 'E' || c[i][j] == 'S' || c[i][j] == 'W' || c[i][j] == 'N'){
					int b = (dd.find(c[i][j]) + 3)%4;
					rep(d,4){
						int nx = j + dx[(b+d)%4];
						int ny = i + dy[(b+d)%4];
						if(c[ny][nx] == '.' || c[ny][nx] == 'X'){
							next[i][j]= make_pair(nx,ny);
							break;
						}
					}
				}
			}
			rep(i,H)rep(j,W) {
				if( c[i][j] == '.' || c[i][j] == 'X'){
					rep(d,4){
						int nx = j + dx[d];
						int ny = i + dy[d];
						if( (c[ny][nx] == 'E' || c[ny][nx] == 'S' || c[ny][nx] == 'W' || c[ny][nx] == 'N') && next[ny][nx] == make_pair(j,i)){
							if(done[i][j]){
								C[ny][nx] = dd[(d + 2)%4]; 
							}else{
								if( c[i][j] != 'X' ) {
									//if( sec < 10 ) cout << c[ny][nx] << " " << endl;
									C[i][j] = dd[(d + 2)%4]; 
									done[i][j] = true;
								}else{ 
									done[i][j] = true;
								}
							}
						}
					}
				}
			}
			//if(sec < 10) rep(i,H) cout << C[i] << endl;
			rep(i,H)rep(j,W) c[i][j] = C[i][j];
			sec++;
		}
		if(!ok) cout << "NA" << endl;
	}
}