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<stdio.h>
int main(){
  int X[]={ 0,-1,0,1, 0,-1,0};
  int Y[]={-1, 0,1,0,-1, 0,1};
  int d[900][4];//x,y,d,c
  char m[30][31];
  int w,h,i,j,k,l,c,xc;
  int x[900],y[900];
  while(1){
    scanf("%d %d",&w,&h);
    if(!(w||h))break;
    scanf("\n");
    c=0;
    k=0;
    xc=0;
    for(i=0;i<h;i++){
      for(j=0;j<=w;j++){
	scanf("%c",&m[i][j]);
	d[k][3]=1;
	if(m[i][j]=='E'){
	  d[k][0]=j;
	  d[k][1]=i;
	  d[k][2]=2;
	  k++;
	}
	if(m[i][j]=='N'){
	  d[k][0]=j;
	  d[k][1]=i;
	  d[k][2]=3;
	  k++;
	}
	if(m[i][j]=='W'){
	  d[k][0]=j;
	  d[k][1]=i;
	  d[k][2]=0;
	  k++;
	}
	if(m[i][j]=='S'){
	  d[k][0]=j;
	  d[k][1]=i;
	  d[k][2]=1;
	  k++;
	}
	if(m[i][j]=='X'){
	  x[xc]=j;
	  y[xc]=i;
	  xc++;
	}
      }
    }
    /*for(i=0;i<k;i++){
      printf("d%d c%d\n",d[i][2],d[i][3]);
      }*/
    for(i=1;i<=180;i++){
      for(j=0;j<k;j++){//mukichange
	if(d[j][3]==0)continue;
	for(l=0;l<4;l++){
	  if(m[d[j][1]+Y[d[j][2]+l]][d[j][0]+X[d[j][2]+l]]=='.'||
	     m[d[j][1]+Y[d[j][2]+l]][d[j][0]+X[d[j][2]+l]]=='X'){
	    d[j][2]+=l-1;//printf("d%d\n",d[j][2]);
	    //d[j][3]=1;
	    if(d[j][2]<0)d[j][2]+=4;
	    if(d[j][2]>3)d[j][2]-=4;
	    break;
	  }
	}
      }//printf("%d\n",d[0][2]);
      for(j=0;j<4;j++){//junbannni idou
	for(l=0;l<k;l++){//printf("%d",d[l][2]);
	  if(d[l][3]==0)continue;
	  if(d[l][2]==j){//printf("%d\n",j);
	    if(m[d[l][1]+Y[1+j]][d[l][0]+X[1+j]]=='.'||
	       m[d[l][1]+Y[1+j]][d[l][0]+X[1+j]]=='X'){
	      if(m[d[l][1]+Y[1+j]][d[l][0]+X[1+j]]=='X')d[l][3]=0;
	      m[d[l][1]][d[l][0]]='.';
	      m[d[l][1]+Y[1+j]][d[l][0]+X[1+j]]='P';
	      d[l][1]+=Y[1+j];
	      d[l][0]+=X[1+j];
	    }
	    /*else if(m[d[l][1]+Y[1+j]][d[l][0]+X[1+j]]=='X'){
	      m[d[l][1]][d[l][0]]='.';
	      c++;
	      d[l][3]=0;
	      }*/
	  }
	}
      }
      for(j=0;j<xc;j++){
	if(m[y[j]][x[j]]=='P'){
	  m[y[j]][x[j]]='X';
	  c++;
	}
      }
      /*for(l=0;l<h;l++){
	for(j=0;j<w;j++){
	  printf("%c",m[l][j]);
	}
	printf("\n");
      }
      printf("%d\n",c);*/
      if(k==c)break;
    }
    if(k==0)i=0;
    if(i==181)printf("NA\n");
    else      printf("%d\n",i);
  }
  return 0;
}

C++: #include <iostream>
#include <cstdlib>

using namespace std;

const int N = 31;

int h, w, p;
char mapData[N][N];
char next[N][N];
int dy[] = {0, -1, 0, 1};
int dx[] = {1, 0, -1, 0};

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

char convertInteger(int d){
   if(d == 0) return 'E';
   if(d == 1) return 'N';
   if(d == 2) return 'W';
   if(d == 3) return 'S';
}

void changeDirection(int y, int x, char c){
   for(int i=0;i<4;++i){
      int d = (convertDirection(c)+3+i)%4;
      int ty = y + dy[d];
      int tx = x + dx[d];
      if(ty<0 || ty>=h) continue;
      if(tx<0 || tx>=w) continue;
      if(mapData[ty][tx] == '.' || mapData[ty][tx] == 'X'){
         mapData[y][x] = convertInteger(d);
         return;
      }
   }
}

void searchPerson(){
   for(int i=0;i<h;++i){
      for(int j=0;j<w;++j){
         if(mapData[i][j] == 'E' || 
            mapData[i][j] == 'N' || 
            mapData[i][j] == 'W' ||
            mapData[i][j] == 'S')
            changeDirection(i, j, mapData[i][j]);
      }
   }
}

void copy(){
   for(int i=0;i<h;++i){
      for(int j=0;j<w;++j){
         mapData[i][j] = next[i][j];
      }
   }
}
void movePerson(int y, int x, int ty, int tx){
   if(mapData[y][x] == 'X'){
      --p;
   }else{
      next[y][x] = mapData[ty][tx];
   }
   next[ty][tx] = '.';
}

void selectPerson(int y, int x){
   for(int i=0;i<4;++i){
      int ty = y + dy[i];
      int tx = x + dx[i];
      if(ty<0 || ty>=h) continue;
      if(tx<0 || tx>=w) continue;
      if(mapData[ty][tx] == '#' || mapData[ty][tx] == '.' || mapData[ty][tx] == 'X') continue;
      if(convertDirection(mapData[ty][tx]) == (i+2)%4){
         movePerson(y, x, ty, tx);
         break;
      }
   }
}

void searchPoint(){
   for(int i=0;i<h;++i){
      for(int j=0;j<w;++j){
         if(mapData[i][j] == '.' || mapData[i][j] == 'X')
            selectPerson(i, j);
      }
   }
   copy();
}

main(){
   while(cin >> w >> h && (h || w)){
      p = 0;
      for(int i=0;i<h;++i){
         for(int j=0;j<w;++j){
            cin >> mapData[i][j];
            if(mapData[i][j] == 'E' || 
               mapData[i][j] == 'N' || 
               mapData[i][j] == 'W' ||
               mapData[i][j] == 'S')
               ++p;
         }
      }
      if(p == 0){
         cout << 0 << endl;
         continue;
      }
      for(int i=0;i<h;++i){
         for(int j=0;j<w;++j){
            next[i][j] = mapData[i][j];
         }
      }
      bool f = false;
      for(int t=1;t<=180;++t){
         searchPerson();
         searchPoint();
         if(p == 0){
            cout << t << endl;
            f = true;
            break;
         }
      }
      if(!f)cout << "NA" << endl;
   }
   return 0;
}