#include<iostream>
#include<vector>
#include<string>
#include<algorithm>
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<cstdio>
#include<sstream>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mp make_pair
#define all(in) in.begin(),in.end()
const double PI=acos(-1);
const double EPS=1e-8;
const int inf=1e9;
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;
int main(){
	int dx[]={0,1,0,-1,0,1,0,-1};
	int dy[]={-1,0,1,0,-1,0,1,0};
	int n,m;
	while(cin>>m>>n,n+m){
		vector<string>in(n);
		rep(i,n)cin>>in[i];
		map<int,map<int,bool> >ma;
		rep(i,n)rep(j,m)if(in[i][j]=='X')ma[i][j]=true;
		rep(i,n)rep(j,m)if(in[i][j]=='N')in[i][j]='2';
		else if(in[i][j]=='E')in[i][j]='1';
		else if(in[i][j]=='S')in[i][j]='0';
		else if(in[i][j]=='W')in[i][j]='3';
		int c=0;
		rep(i,n)rep(j,m)if(isdigit(in[i][j]))c++;
		rep(q,181){
//			cout<<q<<endl;
			if(q==180){
				cout<<"NA"<<endl;
				break;
			}
			vvi tmp(n,vi(m));
			rep(i,n)rep(j,m)if(isdigit(in[i][j])){
				int t=in[i][j]-'0';
				rep(k,4)if(in[i+dx[t+k]][j+dy[t+k]]!='#'&&
					!isdigit(in[i+dx[t+k]][j+dy[t+k]])){
					tmp[i][j]=(t+k)%4+1;
					break;
				}
			}
//			rep(i,n){rep(j,m)cout<<" "<<tmp[i][j];cout<<endl;}
			rep(k,4){
				rep(i,n)rep(j,m)if(tmp[i][j]==k+1){
					if(!isdigit(in[i+dx[k]][j+dy[k]])){
//						cout<<i+dx[k]<<" "<<j+dy[k]<<endl;
						in[i+dx[k]][j+dy[k]]=(tmp[i][j]+2)%4+'0';
						in[i][j]='.';
					}
				}
			}
//			rep(i,n)cout<<in[i]<<endl;cout<<endl;
			rep(i,n)rep(j,m)if(isdigit(in[i][j])&&ma[i][j]){
				c--;
				if(!c){
					cout<<q+1<<endl;
					goto end;
				}
				in[i][j]='X';
			}
//			rep(i,n)cout<<in[i]<<endl;cout<<endl;
		}
		end:;
	}
}