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

class Maze {
public:
	map<char, char> next;
	map<char, char> prev;
	map<char, pair<int,int>> xy;

	Maze(vector<string> maze) : maze(maze), rest(-1) {
		map<char, char> next = { {'N','E'}, {'E','S'}, {'S','W'}, {'W','N'} };
		map<char, char> prev = { {'E','N'}, {'S','E'}, {'W','S'}, {'N','W'} };
		map<char, pair<int,int>> xy = { {'N', {0, -1}}, {'E', {1, 0}}, {'S', {0, 1}}, {'W', {-1, 0}} };
		H = maze.size();
		W = maze[0].size();
		rest = countPeople();
	}

	void move() {
		changeDirection();
		goAhead();
	}

	int countPeople() {
		if (0 <= rest) return rest;
		int count = 0;
		for (string str : maze) {
			for (char c : str) {
				count += isPerson(c);
			}
		}
		return count;
	}

private:
	vector<string> maze;
	int H, W;
	int rest;

	bool isPerson(char c) {
		return (isalpha(c) && c != 'X');
	}

	bool isPassable(char c) {
		return (c == '.' || c == 'X');
	}

	void changeDirection() {
		for (int i=0; i<H; ++i) {
			for (int j=0; j<W; ++j) {
				if ( ! isPerson(maze[i][j])) continue;
				char dir = next[maze[i][j]];
				for (int k=0; k<4; ++k) {
					int x = j + xy[dir].first;
					int y = i + xy[dir].second;
					if (maze[y][x] == '.' || maze[y][x] == 'X') {
						maze[i][j] = dir;
						break;
					}
					dir = prev[dir];
				}
			}
		}
	}

	void goAhead () {
		for (int i=0; i<H; ++i) {
			for (int j=0; j<W; ++j) {
				if ( ! isPassable(maze[i][j])) continue;
				char dir = 'E';
				for (int k=0; k<4; ++k) {
					int x = j + xy[dir].first;
					int y = i + xy[dir].second;
					if (0 <= x && x < W && 0 <= y && y < H && maze[y][x] == next[next[dir]]) {
						maze[y][x] = '.';
						if (maze[i][j] == '.') {
							maze[i][j] = tolower(next[next[dir]]);
						} else {
							rest --;
						}
						break;
					}
					dir = prev[dir];
				}
			}
		}
		for (int i=0; i<(int)maze.size(); ++i) {
			for (int j=0; j<(int)maze[i].size(); ++j) {
				maze[i][j] = toupper(maze[i][j]);
			}
		}
	}
};

int main() {
	int W, H;
	while (cin >> W >> H && (W || H)) {
		vector<string> input(H);
		for (int i=0; i<H; ++i) cin >> input[i];

		Maze maze(input);

		int second = 0;
		while (0 < maze.countPeople() && second <= 180) {
			maze.move();
			second ++;
		}
		if (second <= 180) cout << second << endl;
		else cout << "NA" << endl;
	}
	return 0;
}