#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<cassert>
#include<iostream>
#include<sstream>
#include<string>
#include<vector>
#include<queue>
#include<set>
#include<map>
#include<utility>
#include<numeric>
#include<algorithm>
#include<bitset>
#include<complex>
#include<stack>

using namespace std;

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

string str[40];
int w,h;

bool check(){
	rep(i,h)rep(j,w){
		if(str[i][j]=='#')continue;
		if(str[i][j]=='X')continue;
		if(str[i][j]=='.')continue;
		return false;
	}
	return true;
}

bool inside(int x,int y){
	return 0<=x&&x<w&&0<=y&&y<h;
}

void ch(){
	int dx[]={1,0,-1,0,1,0,-1,0};
	int dy[]={0,-1,0,1,0,-1,0,1};
	char dir[]={'E','N','W','S','E','N','W','S'};
	rep(i,h)rep(j,w){
		if(str[i][j]=='N'){
			for(int k=0;k<4;++k){
				if(!inside(j+dx[k],i+dy[k]))continue;
				if(str[i+dy[k]][j+dx[k]]=='.'||str[i+dy[k]][j+dx[k]]=='X'){
					str[i][j]=dir[k];
					break;
				}
			}
		}else if(str[i][j]=='W'){
			for(int k=1;k<5;++k){
				if(!inside(j+dx[k],i+dy[k]))continue;
				if(str[i+dy[k]][j+dx[k]]=='.'||str[i+dy[k]][j+dx[k]]=='X'){
					str[i][j]=dir[k];
					break;
				}
			}
		}else if(str[i][j]=='S'){
			for(int k=2;k<6;++k){
				if(!inside(j+dx[k],i+dy[k]))continue;
				if(str[i+dy[k]][j+dx[k]]=='.'||str[i+dy[k]][j+dx[k]]=='X'){
					str[i][j]=dir[k];
					break;
				}
			}
		}else if(str[i][j]=='E'){
			for(int k=3;k<7;++k){
//cout<<str[i+dy[k]][j+dx[k]]<<endl;
				if(!inside(j+dx[k],i+dy[k]))continue;
				if(str[i+dy[k]][j+dx[k]]=='.'||str[i+dy[k]][j+dx[k]]=='X'){
					str[i][j]=dir[k];
					break;
				}
			}
		}
	}
}

void mv(){
	string next[40];
	rep(i,40)next[i]=str[i];
	rep(i,h)rep(j,w){
		if(str[i][j]=='E'){
			if(!inside(j+1,i)||str[i][j+1]!='.'&&str[i][j+1]!='X')continue;
			if(inside(j+2,i)&&str[i][j+2]=='W')continue;
			if(inside(j+1,i-1)&&str[i-1][j+1]=='S')continue;
			next[i][j]='.';
			if(next[i][j+1]=='.')next[i][j+1]='E';
		}else if(str[i][j]=='N'){
			if(!inside(j,i-1)||str[i-1][j]!='.'&&str[i-1][j]!='X')continue;
			if(inside(j+1,i-1)&&str[i-1][j+1]=='W')continue;
			if(inside(j,i-2)&&str[i-2][j]=='S')continue;
			if(inside(j-1,i-1)&&str[i-1][j-1]=='S')continue;
			next[i][j]='.';
			if(next[i-1][j]=='.')next[i-1][j]='N';
		}else if(str[i][j]=='W'){
			if(!inside(j-1,i)||str[i][j-1]!='.'&&str[i][j-1]!='X')continue;
			next[i][j]='.';
			if(next[i][j-1]=='.')next[i][j-1]='W';
		}else if(str[i][j]=='S'){
			if(!inside(j,i+1)||str[i+1][j]!='.'&&str[i+1][j]!='X')continue;
			if(inside(j+1,i+1)&&str[i+1][j+1]=='W')continue;
			next[i][j]='.';
			if(next[i+1][j]=='.')next[i+1][j]='S';
		}
	}
	rep(i,40)str[i]=next[i];
}

void pv(){
	rep(i,h)cout<<str[i]<<endl;
}

int main() {
	for(;;){
		cin>>w>>h;
		if(w==0&&h==0)break;
		rep(i,h)cin>>str[i];
		int res;
		for(res=0;res<=180;++res){
			if(check())break;
			ch();
//pv();
			mv();
//pv();
		}
		if(res<=180)cout<<res<<endl;
		else cout<<"NA"<<endl;
	}
	return 0;
}