#include "bits/stdc++.h"
#include<unordered_map>
#include<unordered_set>
#pragma warning(disable:4996)
using namespace std;
using ld =long double;
const ld eps = 1e-9;

bool check(const vector<vector<pair<int, int>>>&humans, int x, int y) {
	for (int i = 0; i < 4; ++i) {
		auto it=find(humans[i].begin(),humans[i].end(),make_pair(x,y));
		if(it!=humans[i].end())return false;
	}
	return true;
}

int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };

int main()
{
	while (true) {
		int W,H;cin>>W>>H;
		if(!W)break;
		vector<vector<int>>field(H,vector<int>(W));

		string name="WSEN";

		vector<vector<pair<int,int>>>humans(4);
		for (int i = 0; i < H; ++i) {
			string st;cin>>st;
			for (int j = 0; j < W; ++j) {
				char ch(st[j]);
				if(ch=='#')field[i][j]=1;
				else if(ch=='.')field[i][j]=0;
				else if(ch=='X')field[i][j]=2;
				else {
					int k=name.find(ch);
					if (k == string::npos) {
						assert(false);
					}
					else {
						field[i][j]=0;
						k=k%4;
						if(k==0)k=2;
						else if(k==2)k=0;
						humans[k].push_back(make_pair(j,i));
					}
				}
			}
		}

		int time;
		for (time = 1; time < 200; ++time) {
			vector<vector<int>>ways(4);
			vector<vector<pair<int, int>>>next_humans(4);
			for (int i = 0; i < 4; ++i) {
				for (auto human : humans[i]) {
					int now_x = human.first;
					int now_y = human.second;

					int ans = 4;

					for (int plus_way = 1; plus_way > -3; --plus_way) {
						int next_way = (i + 4 + plus_way) % 4;

						int next_x = now_x + dx[next_way];
						int next_y = now_y + dy[next_way];

						if (field[next_y][next_x] != 1 && check(humans, next_x, next_y) == true) {
							ans = next_way;
							break;
						}
					}
					ways[i].push_back(ans);
				}
			}

			vector<vector<int>>moved(H, vector<int>(W));

			vector<int>ts = { 2,1,0,3,4 };
			for (int vv = 0; vv < 5; ++vv) {
				for (int i = 0; i < 4; ++i) {
					for (int j = 0; j < humans[i].size(); ++j) {
						int k = ts[vv];
						if (ways[i][j] == k) {
							if (k == 4) {
								next_humans[i].push_back(humans[i][j]);

							}
							else {
								int next_x = humans[i][j].first + dx[ways[i][j]];
								int next_y = humans[i][j].second + dy[ways[i][j]];

								if (moved[next_y][next_x]) {
									next_humans[ways[i][j]].push_back(humans[i][j]);
								}
								else {

									if (field[next_y][next_x] == 2)continue;
									moved[next_y][next_x] = true;
									next_humans[ways[i][j]].push_back(make_pair(next_x, next_y));
								}
							}

						}
					}

				}
			}
		
			humans=next_humans;
			if (all_of(humans.begin(), humans.end(), [](const vector<pair<int, int>>&v) {return v.empty(); })) {
				break;
			}
		}
		if (time > 180) {
			cout<<"NA"<<endl;
		}
		else {
			cout<<time<<endl;
		}
	}
	return 0;
}
