#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <deque>
#include <string>
#include <cmath>
#include <cstdio>
#define FOR(I,A,B) for(int I =(A);I<(B);++I)
#define FORE(I,B) for(int I =1;I<=(B);++I)
#define REP(I,A) FOR(I,0,A)
const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
const char dc[]={'E','N','W','S'};
const char dcc[]={'e','n','w','s'};
using namespace std;

int main() {
	// your code goes here
	int W,H;
	while (cin >> W >> H && W){
	char tmp;
	char maps[32][32]={};
	FORE(i,H)
		FORE(j,W)
			cin >> maps[i][j];
	bool ans;
	int next=0;
	while(true){
		ans=false;
		FORE(jj,W){
			int j=W-jj;
			FORE(i,H){
				REP(k,4)
					if(maps[i][j]==dc[k]){
						REP(l,4){
							int n=(k+l+3)%4;
							if(maps[i+dy[n]][j+dx[n]]=='.'){
								maps[i][j]='x';
								maps[i+dy[n]][j+dx[n]]=dcc[n];
							}
							else if(maps[i+dy[n]][j+dx[n]]=='n' && dc[n]=='E'){
								maps[i][j]='x';
								maps[i+dy[n]][j+dx[n]]=dcc[n];
								maps[i+1][j+1]='N';
							}
							else if(maps[i+dy[n]][j+dx[n]]=='X')
								maps[i][j]='x';
							else{
							REP(g,4)
								if(maps[i+dy[n]][j+dx[n]]==dcc[g]){
									maps[i][j]=dc[n];
									goto label;
								}
								continue;
							}
							label:
							break;
						}
					ans=true;
					break;
					}
			}
		}
		FORE(i,H){
			FORE(j,W){
				if(maps[i][j]=='x')
					maps[i][j]='.';
				REP(k,4)
					if(maps[i][j]==dcc[k])
						maps[i][j]=dc[k];
			//	cout << maps[i][j];
			}
	//	cout << endl;
		}
		if(!ans || next>180)
			break;
		next++;
	}
	if(next>180)
	cout << "NA" << endl;
	else 
	cout << next << endl;
	}
	return 0;
}