#include <iostream>
#include <string>
#include <vector>
#include <map>
using namespace std;

const int dx[] = { 1, 0, -1, 0 };
const int dy[] = { 0, 1, 0, -1 };
const int dd[] = { 1, 0, 3, 2 };
const char ch[] = { 'E', 'S', 'W', 'N' };

class Trl {
public:
	int x,y,c,d;
	Trl(int x, int y, int d) : x(x), y(y), d(d) {}
};
typedef pair<int,int> PII;

int main()
{
	int X,Y;
	while (cin >> X >> Y, X||Y)
	{
		string stg[Y];
		for (int i=0; i<Y; i++)
			cin >> stg[i];

		vector<Trl> v;
		for (int y=0; y<Y; y++)
		for (int x=0; x<X; x++)
		{
			if (stg[y][x] == 'E')
				v.push_back(Trl(x,y,0));
			if (stg[y][x] == 'S')
				v.push_back(Trl(x,y,1));
			if (stg[y][x] == 'W')
				v.push_back(Trl(x,y,2));
			if (stg[y][x] == 'N')
				v.push_back(Trl(x,y,3));
		}

		int ans = 0;
		while (v.size() > 0 && ans <= 180)
		{
			int s = v.size();
			vector<Trl> upd;
			vector<int> nx(s,0), ny(s,0);
			for (int i=0; i<s; i++)
			{
				Trl t = v[i];
				bool f=1;
				for (int k=0; k<4; k++)
				{
					nx[i] = t.x + dx[(t.d+dd[k])%4];
					ny[i] = t.y + dy[(t.d+dd[k])%4];
					if (nx[i] < 0 || nx[i] >= X || ny[i] < 0 || ny[i] >= Y) continue;
					if (!(stg[ny[i]][nx[i]] == '.' || stg[ny[i]][nx[i]] == 'X')) continue;
					t.d = (t.d + dd[k]) % 4;
					f=0;
					break;
				}
				if (f) { nx[i] = t.x; ny[i] = t.y; }
				upd.push_back(t);
			}

			vector<int> cx, cy;
			for (int i=0; i<s-1; i++)
			{
				for (int k=i+1; k<s; k++)
				{
					if (nx[i] == nx[k] && ny[i] == ny[k])
					{
						if ((upd[i].d+1)%4 > (upd[k].d+1)%4)
						{
							nx[k] = v[k].x; ny[k] = v[k].y;
						}
						else
						{
							nx[i] = v[i].x; ny[i] = v[i].y;
						}
					}
				}
			}

			int p=0;
			for (int i=0; i<s; i++)
			{
				if (stg[ny[i]][nx[i]] == 'X')
				{
					stg[v[i].y][v[i].x] = '.';
					upd.erase(upd.begin()+p);
				}
				else
				{
					stg[v[i].y][v[i].x] = '.';
					stg[ny[i]][nx[i]] = ch[upd[p].d];
					upd[p].x = nx[i];
					upd[p].y = ny[i];
					p++;
				}
			}
			v = upd;
			ans++;
		}

		if (ans <= 180)
			cout << ans << endl;
		else
			cout << "NA" << endl;
	}
}