#include<cstdio>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<cstring>
#include<cctype>
#include<complex>
#include<iostream>
#include<sstream>
#include<algorithm>
#include<functional>
#include<vector>
#include<string>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<bitset>
using namespace std;

const int dx[] = {1,0,-1,0};
const int dy[] = {0,-1,0,1};
#define INF 1e+8
#define EPS 1e-10
#define PB push_back
#define fi first
#define se second
#define ll long long 
#define reps(i,j,k) for(int i = (j); i < (k); i++)
#define rep(i,j) reps(i,0,j)
typedef pair<int,int> Pii;
typedef vector<int> vi;
class Data{
	public:
	int y;
	int x;
	int type;
	Data(){}
	Data(int _y,int _x,int _type){
		y = _y;
		x = _x;
		type = _type;
	}
	bool operator==(const Data &a)const{
		return (y == a.y && x == a.x);
	}
};
int chenge(char info){
	if(info == 'E')return 0;
	if(info == 'N')return 1;
	if(info == 'W')return 2;
	if(info == 'S')return 3;
}
bool check(char info){
	if(info != '#' && info != 'X' && info != '.')return true;
	return false;
}
int main(){
	int w,h;
	while(scanf("%d%d",&w,&h),w){
		char stage[32][32]={{0}};
		vector < Data > player;
		rep(i,h){
			scanf("%s",stage[i]);
			rep(j,w){
				if(check(stage[i][j])){
					player.PB(Data(i,j,chenge(stage[i][j])));
				}
			}
		}

		int cnt = 0;
		while(player.size() > 0){
			/*
			rep(i,h){
				printf("%s\n",stage[i]);
			}
			printf("type:%d\n",player[0].type);
			puts("-------------------");
			*/
			cnt++;
			if(cnt > 180){
				cnt = -1;
				break;
			}
			int len = player.size();
			bool next[32][32]={{false}};
			int from[32][32]={{0}};
			vector < Data > memo;
			vector < Data > del;
			rep(i,len){
				Data d = player[i];
				rep(j,4){
					int k = (d.type+j+3)%4;
					int nx = d.x + dx[k];
					int ny = d.y + dy[k];
					if(ny < 0 || ny > h-1 || nx < 0 || nx > w-1)continue;
					if(stage[ny][nx] == '.' || stage[ny][nx] == 'X'){
						memo.PB(Data(ny,nx,k));
						next[ny][nx] = true;
						from[d.y][d.x] = i+1;
						break;
					}
				}
			}
			rep(i,memo.size()){
				if(!next[memo[i].y][memo[i].x]){
					player[i].type = memo[i].type;
					continue;
				}
				rep(j,4){
					int ny = memo[i].y+dy[j];
					int nx = memo[i].x+dx[j];
					if(ny < 0 || ny > h-1 || nx < 0 || nx > w-1)continue;
					if(from[ny][nx] != 0 && from[ny][nx] != i+1)continue;
					if(from[ny][nx] == i+1){
						stage[ny][nx] = '.';
						player[i].y = memo[i].y;
						player[i].x = memo[i].x;
						player[i].type = memo[i].type;
						if(stage[memo[i].y][memo[i].x] == 'X'){
							del.PB(player[i]);
						}
						else{
							stage[player[i].y][player[i].x] = memo[i].type+48;
						}
						next[memo[i].y][memo[i].x] = false;
						break;
					}
				}
			}
			rep(i,del.size()){
				vector<Data>::iterator it = remove(player.begin(),player.end(),del[i]);
				player.erase(it,player.end());
			}
		}
		if(cnt == -1)puts("NA");
		else printf("%d\n",cnt);
	}
	return 0;
}