#include<list>
#include<iostream>

#define	mp	make_pair
#define	pb	push_back

using namespace std;

typedef	pair<int,int>	pii;

const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};

int main(){
	char maze[30][31];
	int chk[30][30];

	for(int w,h;cin>>w>>h,w;){
		for(int i=0;i<h;i++)	cin>>maze[i];

		list<pii> man;
		for(int i=0;i<h;i++)for(int j=0;j<w;j++){
			if(maze[i][j]!='.' && maze[i][j]!='X' && maze[i][j]!='#')
				man.pb(mp(i,j));
				if     (maze[i][j]=='E')	maze[i][j]=0;
				else if(maze[i][j]=='N')	maze[i][j]=1;
				else if(maze[i][j]=='W')	maze[i][j]=2;
				else if(maze[i][j]=='S')	maze[i][j]=3;
		}

		int ans=-1;
		for(int t=0;t<=180;t++){
			if(man.empty()){ ans=t; break; }

			for(int i=0;i<h;i++)for(int j=0;j<w;j++)	chk[i][j]=777;
			list<pii>::iterator it;
			for(it=man.begin();it!=man.end();it++){
				int y=it->first,x=it->second;
				for(int i=0,j=(maze[y][x]+3)%4;i<4;i++,j=(j+1)%4){
					int yy=y+dy[j],xx=x+dx[j];
					if(0<=yy && yy<h && 0<=xx && xx<w
					&&(maze[yy][xx]=='.' || maze[yy][xx]=='X')){
						maze[y][x]=j;
						chk[yy][xx]=min(chk[yy][xx],(j+2)%4);
						break;
					}
				}
			}

			for(it=man.begin();it!=man.end();){
				int y=it->first,x=it->second;
				int yy=y+dy[maze[y][x]],xx=x+dx[maze[y][x]];
				if(0<=yy && yy<h && 0<=xx && xx<w && (chk[yy][xx]+2)%4==maze[y][x]){	// movable
					*it=mp(yy,xx);
					if(maze[yy][xx]=='.')	maze[yy][xx]=maze[y][x];
					maze[y][x]='.';
				}

				if(maze[it->first][it->second]=='X')	it=man.erase(it);
				else	it++;
			}
		}

		if(~ans)	cout<<ans<<endl;
		else		cout<<"NA"<<endl;
	}

	return 0;
}