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<vector>
#include<list>
#include<algorithm>
#include<iostream>
#include<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
using namespace std;
int main(){
  int i,j,k;
  int p[4]={0,1,0,-1},q[4]={1,0,-1,0};
  int a[32][32],w,h,t,m,n;
  int *fx,*fy,*tx,*ty;
  memset(a,-1,sizeof(a));
  while(cin>>w>>h&&w+h){
    for(i=1;i<h+1;i++){
      string s;
      cin>>s;
      for(j=1;j<w+1;j++){
	if(s[j-1]=='X')
	  a[j][i]=-3;
	else if(s[j-1]=='.')
	  a[j][i]=-2;
	else if(s[j-1]=='#')
	  a[j][i]=-1;
	else if(s[j-1]=='E')
	  a[j][i]=0;
	else if(s[j-1]=='N')
	  a[j][i]=1;
	else if(s[j-1]=='W')
	  a[j][i]=2;
	else if(s[j-1]=='S')
	  a[j][i]=3;
      }
    }
    n=0;
    for(i=1;i<h+1;i++){
      for(j=1;j<w+1;j++){
	if(a[j][i]>=0)
	  n++;
      }
    }
    fx=new int[n];
    fy=new int[n];
    tx=new int[n];
    ty=new int[n];
    for(t=0;t<181&&n;t++){
      /*      
      for(i=1;i<h+1;i++){
	for(j=1;j<w+1;j++){
	  if(a[j][i]==-3)
	    printf("X");
	  else if(a[j][i]==-2)
	    printf(".");
	  else if(a[j][i]==-1)
	    printf("#");
	  else if(a[j][i]==0)
	    printf("E");
	  else if(a[j][i]==1)
	    printf("N");
	  else if(a[j][i]==2)
	    printf("W");
	  else if(a[j][i]==3)
	    printf("S");
	}
	cout<<endl;
      }
      cout<<endl;      
      */
      for(i=1;i<h+1;i++){
	for(j=1;j<w+1;j++){
	  if(a[j][i]>=0){
	    for(k=0;k<4;k++){
	      if(a[j+p[(k+a[j][i])%4]][i+q[(k+a[j][i])%4]]<-1)
		break;
	    }
	    if(k!=4)
	      a[j][i]=(k+a[j][i]+3)%4;	    
	  }
	}
      }
      m=0;
      for(i=1;i<h+1;i++){
	for(j=1;j<w+1;j++){
	  if(a[j][i]<-1){
	    for(k=1;k<5;k++){
	      if(a[j+p[k%4]][i+q[k%4]]>=0&&(k+1)%4==a[j+p[k%4]][i+q[k%4]])
		break;
	    }
	    if(k!=5){
	      fx[m]=j+p[k%4];
	      fy[m]=i+q[k%4];
	      tx[m]=j;
	      ty[m]=i;
	      m++;
	    }
	  }
	}
      }
      for(i=0;i<m;i++){
	if(a[tx[i]][ty[i]]==-3){
	  a[fx[i]][fy[i]]=-2;
	  n--;
	}else{
	  a[tx[i]][ty[i]]=a[fx[i]][fy[i]];
	  a[fx[i]][fy[i]]=-2;
	}
      }
    }
    delete[]fx;
    delete[]fy;
    delete[]tx;
    delete[]ty;
    if(t==181)
      cout<<"NA"<<endl;
    else
      cout<<t<<endl;
  }
  return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<vector>
using namespace std;

#define REP(i,n) for(int i=0;i<(int)(n);++i)

int R, C;
string table[32];
int num[32][32];

const int dr[] = {0, -1, 0, 1};
const int dc[] = {1, 0, -1, 0};

const string aim = "ENWS";
inline int isPerson(int ch) {
  if( ch == 'E' ) return 0;
  if( ch == 'N' ) return 1;
  if( ch == 'W' ) return 2;
  if( ch == 'S' ) return 3;
  return -1;
}

int solve() {
  for(int turn = 0; turn < 180; turn++) {
    REP(i, R) REP(j, C) num[i][j] = 0;
    int o = 0;
    REP(r, R) REP(c, C) {
      if( isPerson( table[r][c] ) >= 0 ) {
        o++;
        int d = isPerson(table[r][c]);
        for(int k = 0; k < 4; k++) {
          int nr = r + dr[(k + d + 3) % 4];
          int nc = c + dc[(k + d + 3) % 4];
          if( table[nr][nc] == '.' || table[nr][nc] == 'X' ) {
            d = (k + d + 3) % 4;
            ++num[nr][nc];
            break;
          }
        }
        table[r][c] = aim[d];
      }
    }
    if( o == 0 ) return turn;

//     REP(i, R) cout << table[i] << endl;
//     cout << endl;

    REP(r, R) REP(c, C) {
      if( num[r][c] > 0 ) {
        REP(k, 4) {
          int nr = r + dr[k];
          int nc = c + dc[k];
          if( 0 <= nr && nr < R && 0 <= nc && nc < C && isPerson( table[nr][nc] ) >= 0 ) {
            if( table[r][c] == 'X' ) {
              table[nr][nc] = '.';
            } else {
              swap( table[r][c], table[nr][nc] );
            }
            break;
          }
        }
      }
    }

  }
  return -1;
}
int main() {
  for(;;) {
    cin >> C >> R; if( R == 0 && C == 0 ) break;
    REP(i, R) cin >> table[i];

    int res = solve();
    if( res == -1 ) cout << "NA" << endl;
    else cout << res << endl;
  }
  return 0;
}