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<algorithm>
using namespace std;

const string Direction = {"ENWS"};
const int Next[4][2] = {{0, 1}, {-1, 0}, {0, -1}, {1, 0}};

int main() {
    int w, h;
    while(cin >> w >> h, w | h) {
        int time;
        vector<string> map(h);
        for(int i = 0; i < h; ++i) cin >> map[i];

        for(time = 0; time <= 180; ++time) {
            bool ok = true;
            for(const auto& line: map) for(const auto& c: line)
                if(Direction.find(c) != string::npos) ok = false;
            if(ok) break;
            // turn
            for(int i = 0; i < h; ++i) for(int j = 0; j < w; ++j) {
                int index = Direction.find(map[i][j]);
                if(index == string::npos) continue;
                index = (index - 1 + 4) % 4;
                for(int k = 0; k < 5; ++k) {
                    int y = i + Next[index][0];
                    int x = j + Next[index][1];
                    if(map[y][x] == '.' || map[y][x] == 'X') break;
                    index = (index + 1) % 4;
                }
                map[i][j] = Direction[index];
            }
            // move
            vector<vector<int>> used(h, vector<int>(w, 0));
            for(int i = 0; i < h; ++i) for(int j = 0; j < w; ++j) {
                if(map[i][j] != '.' && map[i][j] != 'X') continue;
                for(int d = 0; d < 4; ++d) {
                    int y = i + Next[d][0];
                    int x = j + Next[d][1];
                    int index = Direction.find(map[y][x]);
                    if(index == string::npos) continue;
                    if((index - d + 4) % 4 != 2) continue;
                    if(used[y][x]) continue;
                    used[i][j] = 1;
                    if(map[i][j] == '.') swap(map[i][j], map[y][x]);
                    else map[y][x] = '.';
                    break;
                }
            }
        }

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

C++: #include<iostream>
#define ck(a,b) 0<=a&&a<b
#define enws(a) (a=='E'||a=='N'||a=='W'||a=='S')
#define dir(a) (a!='E'?a!='N'?a!='W'?3:2:1:0)
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
int main(){
	int w,h,t,rest;char m[31][31],nm[31][31];
	while(cin>>w>>h,w){
		rest=0;
		rep(i,h){
			cin>>m[i];
			rep(j,w)if(enws(m[i][j]))rest++;
		}
		for(t=0;rest&&t<181;t++){
			rep(i,h)rep(j,w){
				if(enws(m[i][j])){
					int cd=dir(m[i][j]),nd,ny,nx;
					rep(d,4){
						nd=cd+d+3&3;
						ny=i+dy[nd],nx=j+dx[nd];
						if(ck(ny,h)&&ck(nx,w)&&(m[ny][nx]=='.'||m[ny][nx]=='X')){
							m[i][j]="ENWS"[nd]; break;
						}
					}
				}
				nm[i][j]=m[i][j];
			}
			rep(i,h)rep(j,w)if(m[i][j]=='.'||m[i][j]=='X'){
				rep(d,4){
					int ny=i+dy[d],nx=j+dx[d];
					if(ck(ny,h)&&ck(nx,w)&&m[ny][nx]=="WSEN"[d]){
						if(m[i][j]=='.')nm[i][j]=m[ny][nx];
						else rest--;
						nm[ny][nx]='.';
						break;
					}
				}
			}
			rep(i,h)rep(j,w)m[i][j]=nm[i][j];
		}
		if(t<=180)cout<<t<<endl;
		else cout<<"NA"<<endl;
	}
	return 0;
}

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

int W, H, N;
int a[30][30];
int d[900];
bool x[900];

int dd[4] = {3, 0, 1, 2};
int dr[4] = {0, 1, 0, -1};
int dc[4] = {-1, 0, 1, 0};

bool input() {
  cin >> W >> H;
  if (!W && !H) {
    return false;
  }
  int id = 0;
  for (int r = 0; r < H; ++r) {
    string str;
    cin >> str;
    for (int c = 0; c < W; ++c) {
      if (str[c] == '#') {
        a[r][c] = -2;
      } else if (str[c] == '.') {
        a[r][c] = 0;
      } else if (str[c] == 'X') {
        a[r][c] = -1;
      } else {
        a[r][c] = ++id;
        if (str[c] == 'W') {
          d[id] = 0;
        } else if (str[c] == 'S') {
          d[id] = 1;
        } else if (str[c] == 'E') {
          d[id] = 2;
        } else if (str[c] == 'N') {
          d[id] = 3;
        }
      }
    }
  }
  N = id;
  return true;
}

void solve() {
  int t = 0;
  int u = 0;
  while (t < 180) {
    if (u == N) {
      break;
    }
    ++t;
    for (int r = 0; r < H; ++r) {
      for (int c = 0; c < W; ++c) {
        if (a[r][c] <= 0) {
          continue;
        }
        int id = a[r][c];
        for (int i = 0; i < 4; ++i) {
          int nd = (d[id] + dd[i]) % 4;
          int np = a[r + dr[nd]][c + dc[nd]];
          if (!np || np == -1) {
            d[id] = nd;
            break;
          }
        }
      }
    }

    for (int i = 1; i <= N; ++i) {
      x[i] = false;
    }
    for (int i = 0; i < 4; ++i) {
      for (int r = 0; r < H; ++r) {
        for (int c = 0; c < W; ++c) {
          if (a[r][c] <= 0) {
            continue;
          }
          int id = a[r][c];
          if (d[id] != i) {
            continue;
          }
          if (x[id]) {
            continue;
          }
          x[id] = true;
          int np = a[r + dr[i]][c + dc[i]];
          if (!np) {
            a[r][c] = 0;
            a[r + dr[i]][c + dc[i]] = id;
          } else if (np == -1) {
            a[r][c] = 0;
            ++u;
          }
        }
      }
    }
  }
  if (t <= 180) {
    cout << t << endl;
  } else {
    cout << "NA" << endl;
  }
}

int main() {
  while (input()) {
    solve();
  }
  return 0;
}