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 <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() {
  if (!N) {
    cout << "0" << endl;
  }

  int t = 0;
  int u = 0;
  while (t <= 180) {
    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 (u == N) {
      break;
    }
    ++t;
  }
  if (t <= 180) {
    cout << t << endl;
  } else {
    cout << "NA" << endl;
  }
}

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

C++: #include<iostream>
#include<algorithm>
using namespace std;
struct State{char x[35][35];};
int H,W,dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};State S;char f[5]="NESW";
int solve(State V,int depth){
	if(depth==31)return 99999999;
	bool OK=true;
	for(int i=0;i<H;i++){
		for(int j=0;j<W;j++){
			if(V.x[i][j]>='A' && V.x[i][j]<='W')OK=false;
		}
	}
	if(OK==true)return depth;
	vector<int>G[30][30];
	for(int i=0;i<H;i++){
		for(int j=0;j<W;j++){
			if(V.x[i][j]<'A' || V.x[i][j]>'W')continue;
			
			int dr=0;for(int k=0;k<4;k++){if(V.x[i][j]==f[k])dr=k;}
			for(int k=dr+5;k>=dr-2;k--){
				int ex=i+dx[k%4],ey=j+dy[k%4];
				if(V.x[ex][ey]=='X' || V.x[ex][ey]=='.'){
					V.x[i][j]=f[k%4];
					G[ex][ey].push_back((11-k)%4);break;
				}
			}
		}
	}
	State I=V;
	for(int i=0;i<H;i++){
		for(int j=0;j<W;j++){
			if(G[i][j].size()>=1){
				sort(G[i][j].begin(),G[i][j].end());
				int J=(11-G[i][j][0])%4;
				int fx=i-dx[J],fy=j-dy[J];
				if(I.x[i][j]!='X'){I.x[i][j]=I.x[fx][fy];}
				I.x[fx][fy]='.';
			}
		}
	}
	return solve(I,depth+1);
}
int main(){
	while(true){
		cin>>W>>H;if(W==0 && H==0)break;
		for(int i=0;i<H;i++){for(int j=0;j<W;j++)cin>>S.x[i][j];}
		int ans=solve(S,0);
		if(ans>180)cout<<"NA"<<endl;else cout<<ans<<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<set>
#include<map>
using namespace std;

typedef pair<int,int> P;

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

char inv_dir(int a){
  if(a==0)return 'E';
  if(a==1)return 'N';
  if(a==2)return 'W';
  return 'S';
}

int main(){
  int h,w;
  string grid[30];
  int dx[] = {1,0,-1,0},dy[] = {0,-1,0,1};

  while(cin >> w >> h && (w||h)){
    for(int i=0;i<h;i++)cin >> grid[i];

    int ans = 0;
    for(;;){
      if(ans>180)break;
      set<P> s;

      for(int i=0;i<h;i++){
	for(int j=0;j<w;j++){
	  int d = dir(grid[i][j]);
	  if(0<=d){
	    for(int k=-1;k<3;k++){
	      int dd = (d+k+4)%4;
	      int sy = i+dy[dd], sx = j+dx[dd];
	      if(sy<0 || sx<0 || h<=sy || w<=sx)continue;
	      if(grid[sy][sx] == '.' || grid[sy][sx] == 'X'){
		grid[i][j] = inv_dir(dd);
		s.insert(P(sy,sx));
		break;
	      }
	    }
	  }
	}
      }

      if(s.empty())break;
      set<P>::iterator ite;
      for(ite=s.begin();ite!=s.end();ite++){
	P p = *ite;
	for(int i=0;i<4;i++){
	  int sy = p.first+dy[i], sx = p.second+dx[i];
	  if(sy<0 || sx<0 || h<=sy || w<=sx)continue;
	  int dd = (i+2)%4;
	  if(dir(grid[sy][sx])==dd){
	    grid[sy][sx] = '.';
	    if(grid[p.first][p.second]!='X')grid[p.first][p.second] = inv_dir(dd);
	    break;
	  }
	}
      }
      ans++;
    }
    if(ans>180)cout << "NA\n";
    else cout << ans << endl;
  }
}