#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstdio>
#include <cstring>
#include <iterator>
#include <bitset>
//#include <utility>
//#include <memory>
//#include <functional>
//#include <deque>
//#include <cctype>
//#include <ctime>
//#include <numeric>
//#include <list>
//#include <iomanip>

//#if __cplusplus >= 201103L
//#include <array>
//#include <tuple>
//#include <initializer_list>
//#include <unordered_set>
//#include <unordered_map>
//#include <forward_list>
//
//#define cauto const auto&
//#else

//#endif

using namespace std;


namespace{
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef vector<int> vint;
typedef vector<vector<int> > vvint;
typedef vector<long long> vll, vLL;
typedef vector<vector<long long> > vvll, vvLL;

#define VV(T) vector<vector< T > >

template <class T>
void initvv(vector<vector<T> > &v, int a, int b, const T &t = T()){
    v.assign(a, vector<T>(b, t));
}

template <class F, class T>
void convert(const F &f, T &t){
    stringstream ss;
    ss << f;
    ss >> t;
}


#define reep(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) reep((i),0,(n))
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define F first
#define S second
#define mkp make_pair
#define RALL(v) (v).rbegin(),(v).rend()


#define MOD 1000000007LL
#define EPS 1e-8
static const int INF=1<<24;
}
int dx[] = {1,0,-1,0};
int dy[] = {0,-1,0,1};
 
string s = "ENWS";
 
int main(){
    int w, h;
    while(cin >> w >> h, w || h){
        VV(char) vv(w, vector<char>(h));
        rep(i,h) rep(j,w) cin >> vv[j][i];
        int res = -1;
        rep(time, 180) {
            int man = 0;
            rep(j,h){
                rep(i,w){
                    rep(l,4){
                        if(vv[i][j]==s[l]){
                            man++;
                            rep(k,4) {
                                int d = (l+3+k)%4;
                                int xx = i+dx[d];
                                int yy = j+dy[d];
                                if (vv[xx][yy]=='X'||vv[xx][yy]=='.') {
                                    vv[i][j] = s[d];
                                    goto OUT;
                                }
                            }
                        }
                    }
                    OUT:;
                }
            }
            vector< vector<char> > next(w, vector<char>(h));
            next = vv;
            rep(i,w){
                rep(j,h){
                    if (vv[i][j] != '.' && vv[i][j] != 'X') continue;
                    rep(k,4){
                        int xx = i+dx[k];
                        int yy = j+dy[k];
                        if (xx<0||xx>=w||yy<0||yy>=h) continue;
 
                        if (vv[xx][yy] == s[(k+2)%4]){
                            if (vv[i][j] == '.')
                            next[i][j] = vv[xx][yy];
                            else
                            man--;
                            next[xx][yy] = '.';
                            break;
                        }
                    }
                }
            }
            if (man==0){
                res = time + 1;
                break;
            }
            vv = next;
        }
        if (res>=0){
          cout << res << endl;
        }
        else{
          cout << "NA" << endl;
        }
    }
    return 0;
}

Measured memory_bytes: 1240