#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
using namespace std;

typedef istringstream ISS;
typedef ostringstream OSS;
typedef vector<string> VS;
typedef int INT;
typedef vector<INT> VI;
typedef vector<VI> VVI;
typedef pair <INT, INT> II;
typedef vector <II> VII;

template<class T> ostream& operator << ( ostream& os, vector<T> v ) {
    for ( typename vector<T>::iterator it_i = v.begin(); it_i != v.end(); ++it_i ) {
        os << *it_i << ", ";
    }
    return os;
}


VS M;
int w, h;

void input() {
    M = VS(h);
    for ( int i = 0; i < h; ++ i ) {
        cin >> M[i];
    }
}

bool isHuman( char c ) {
    return c == 'E' || c == 'N' || c == 'W' || c == 'S';
}

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

bool goal() {
    for ( int i = 0; i < h; ++ i ) {
        for ( int j = 0; j < w; ++ j ) {
            if ( isHuman( M[i][j] ) ) return false;
        }
    }
    return true;
}

void print() {
    for ( int i = 0; i < h; ++ i ) {
        cout << M[i] << endl;
    }
    cout << endl;
}

bool isValidPos( int r, int c ) {
    return r >= 0 && r < h && c >= 0 && c < w;
}

char getDirection( int r1, int c1, int r2, int c2 ) {
    const int dr[4] = { 0, -1, 0, 1 };
    const int dc[4] = { 1, 0, -1, 0 };
    const string ds = "ENWS";
    int r = r2 - r1;
    int c = c2 - c1;
    for ( int i = 0; i < 4; ++ i ) {
        if ( dr[i] == r && dc[i] == c ) {
            return ds[i];
        }
    }
    return '@';
}

void rotate() {
    const int dr[4] = { 1, 0, -1, 0 };
    const int dc[4] = { 0, 1, 0, -1 };
    const string ds = "SENW";
    for ( int i = 0; i < h; ++ i ) {
        for ( int j = 0; j < w; ++ j ) {
            if ( ! isHuman( M[i][j] ) ) continue;
            for ( int off = 0; off < 4; ++ off ) {
                if ( ds[off] == M[i][j] ) {
                    for ( int k = 0; k < 4; ++ k ) {
                        int di = ( ( off + k == 0 ) ? 3 : ( off + k - 1 ) ) % 4;
                        int nr = i + dr[di];
                        int nc = j + dc[di];
                        if ( ! isValidPos( nr, nc ) ) continue;
                        if ( ! isEmptyCell( M[nr][nc] ) ) continue;
                        M[i][j] = getDirection( i, j, nr, nc );
                        goto out_1;
                    }
                }
            }
        out_1:;
        }
    }
}

void move() {
    const int dr[4] = { 0, -1, 0, 1 };
    const int dc[4] = { 1, 0, -1, 0 };
    const string ds = "WSEN";
    VS Mnext = M;
    for ( int i = 0; i < h; ++ i ) {
        for ( int j = 0; j < w; ++ j ) {
            if ( M[i][j] == '.' ) {
                for ( int k = 0; k < 4; ++ k ) {
                    int nr = i + dr[k];
                    int nc = j + dc[k];
                    if ( ! isValidPos( nr, nc ) ) continue;
                    if ( M[nr][nc] == ds[k] ) {
                        Mnext[i][j] = Mnext[nr][nc];
                        Mnext[nr][nc] = '.';
                        goto out_1;
                    }
                }
            }
            if ( M[i][j] == 'X' ) {
                for ( int k = 0; k < 4; ++ k ) {
                    int nr = i + dr[k];
                    int nc = j + dc[k];
                    if ( ! isValidPos( nr, nc ) ) continue;
                    if ( M[nr][nc] == ds[k] ) {
                        Mnext[nr][nc] = '.';
                        goto out_1;
                    }
                }
            }
        out_1:;
        }
    }
    M = Mnext;
}

int solve() {
    for ( int i = 0; i <= 180; ++ i ) {
        if ( goal() ) return i;
        rotate();
        move();
    }
    return -1;
}

void output( int t ) {
    if ( t == -1 ) {
        cout << "NA" << endl;
    } else {
        cout << t << endl;
    }
}

int main() {
    while ( cin >> w >> h ) {
        if ( w == 0 && h == 0 ) break;
        input();
        int ret = solve();
        output( ret );
    }
    return 0;
}