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 <sstream>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
using namespace std;

typedef istringstream ISS;
typedef ostringstream OSS;
typedef vector<string> VS;
typedef int INT;
typedef vector<INT> VI;
typedef vector<VI> VVI;
typedef pair <INT, INT> II;
typedef vector <II> VII;

template<class T> ostream& operator << ( ostream& os, vector<T> v ) {
    for ( typename vector<T>::iterator it_i = v.begin(); it_i != v.end(); ++it_i ) {
        os << *it_i << ", ";
    }
    return os;
}


VS M;
int w, h;

void input() {
    M = VS(h);
    for ( int i = 0; i < h; ++ i ) {
        cin >> M[i];
    }
}

bool isHuman( char c ) {
    return c == 'E' || c == 'N' || c == 'W' || c == 'S';
}

bool isEmptyCell( char c ) {
    return c == '.' || c == 'X';
}

bool goal() {
    for ( int i = 0; i < h; ++ i ) {
        for ( int j = 0; j < w; ++ j ) {
            if ( isHuman( M[i][j] ) ) return false;
        }
    }
    return true;
}

void print() {
    for ( int i = 0; i < h; ++ i ) {
        cout << M[i] << endl;
    }
    cout << endl;
}

bool isValidPos( int r, int c ) {
    return r >= 0 && r < h && c >= 0 && c < w;
}

char getDirection( int r1, int c1, int r2, int c2 ) {
    const int dr[4] = { 0, -1, 0, 1 };
    const int dc[4] = { 1, 0, -1, 0 };
    const string ds = "ENWS";
    int r = r2 - r1;
    int c = c2 - c1;
    for ( int i = 0; i < 4; ++ i ) {
        if ( dr[i] == r && dc[i] == c ) {
            return ds[i];
        }
    }
    return '@';
}

void rotate() {
    const int dr[4] = { 1, 0, -1, 0 };
    const int dc[4] = { 0, 1, 0, -1 };
    const string ds = "SENW";
    for ( int i = 0; i < h; ++ i ) {
        for ( int j = 0; j < w; ++ j ) {
            if ( ! isHuman( M[i][j] ) ) continue;
            for ( int off = 0; off < 4; ++ off ) {
                if ( ds[off] == M[i][j] ) {
                    for ( int k = 0; k < 4; ++ k ) {
                        int di = ( ( off + k == 0 ) ? 3 : ( off + k - 1 ) ) % 4;
                        int nr = i + dr[di];
                        int nc = j + dc[di];
                        if ( ! isValidPos( nr, nc ) ) continue;
                        if ( ! isEmptyCell( M[nr][nc] ) ) continue;
                        M[i][j] = getDirection( i, j, nr, nc );
                        goto out_1;
                    }
                }
            }
        out_1:;
        }
    }
}

void move() {
    const int dr[4] = { 0, -1, 0, 1 };
    const int dc[4] = { 1, 0, -1, 0 };
    const string ds = "WSEN";
    VS Mnext = M;
    for ( int i = 0; i < h; ++ i ) {
        for ( int j = 0; j < w; ++ j ) {
            if ( M[i][j] == '.' ) {
                for ( int k = 0; k < 4; ++ k ) {
                    int nr = i + dr[k];
                    int nc = j + dc[k];
                    if ( ! isValidPos( nr, nc ) ) continue;
                    if ( M[nr][nc] == ds[k] ) {
                        Mnext[i][j] = Mnext[nr][nc];
                        Mnext[nr][nc] = '.';
                        goto out_1;
                    }
                }
            }
            if ( M[i][j] == 'X' ) {
                for ( int k = 0; k < 4; ++ k ) {
                    int nr = i + dr[k];
                    int nc = j + dc[k];
                    if ( ! isValidPos( nr, nc ) ) continue;
                    if ( M[nr][nc] == ds[k] ) {
                        Mnext[nr][nc] = '.';
                        goto out_1;
                    }
                }
            }
        out_1:;
        }
    }
    M = Mnext;
}

int solve() {
    for ( int i = 0; i <= 180; ++ i ) {
        if ( goal() ) return i;
        rotate();
        move();
    }
    return -1;
}

void output( int t ) {
    if ( t == -1 ) {
        cout << "NA" << endl;
    } else {
        cout << t << endl;
    }
}

int main() {
    while ( cin >> w >> h ) {
        if ( w == 0 && h == 0 ) break;
        input();
        int ret = solve();
        output( ret );
    }
    return 0;
}