#include<iostream>
#include<string>
#include<algorithm>
#include<set>

char field[30][30];

int input(int h,int w);
char rotate(int x,int y);
int move(int h,int w,int remain);

int main()
{
	while(1)
	{
		int h,w,remain,temp;
		std::cin>>w>>h;
		if(h==0&&w==0)break;
		remain=input(h,w);
		int count;
		
		for(count=0;count<=180&&remain>0;count++)
		{
			for(int y=0;y<h;y++)
			{
				for(int x=0;x<w;x++)
				{
					field[y][x]=rotate(x,y);
				}
			}
			remain=move(h,w,remain);
		}
		if(count>180){std::cout<<"NA"<<std::endl;}
		else{std::cout<<count<<std::endl;}
	}
	return 0;
}

int input(int h,int w)
{
	std::string buf;
	int num=0;
	for(int i=0;i<h;i++)
	{
		std::cin>>buf;
		for(int j=0;j<w;j++)
		{
			field[i][j]=buf[j];
			if(field[i][j]=='N'||field[i][j]=='E'||field[i][j]=='S'||field[i][j]=='W')num++;
		}
	}
	return num;
}

char rotate(int x,int y)
{
	char direction=field[y][x];
	char dir;
	switch(direction)//最初は右を向く
	{
	case 'E':
		dir='W';
		break;
	case 'N':
		dir='S';
		break;
	case 'W':
		dir='E';
		break;
	case 'S':
		dir='N';
		break;
	default:
		return direction;
	}
	for(int i=0;i<=4;i++)
	{
		bool determined=false;
		switch(dir)
		{
		case 'E':
			dir='N';
			if(field[y-1][x]=='.'||field[y-1][x]=='X')
			{
				determined=true;
			}
			break;
		case 'N':
			dir='W';
			if(field[y][x-1]=='.'||field[y][x-1]=='X')
			{
				determined=true;
			}
			break;
		case 'W':
			dir='S';
			if(field[y+1][x]=='.'||field[y+1][x]=='X')
			{
				determined=true;
			}
			break;
		case 'S':
			dir='E';
			if(field[y][x+1]=='.'||field[y][x+1]=='X')
			{
				determined=true;
			}
			break;
		}
		if(determined)break;
	}
	
	return dir;
}

int move(int h,int w,int remain)
{
	std::set<std::pair<int,int> > visited;
	for(int y=0;y<h;y++)
	{
		for(int x=0;x<w;x++)
		{
			if(field[y][x]=='.')
			{
				if(field[y][x+1]=='W'&&visited.find(std::pair<int,int>(x+1,y))==visited.end())
				{
					std::swap(field[y][x],field[y][x+1]);
					visited.insert(std::pair<int,int>(x,y));
				}
				else if(field[y-1][x]=='S'&&visited.find(std::pair<int,int>(x,y-1))==visited.end())
				{
					std::swap(field[y][x],field[y-1][x]);
					visited.insert(std::pair<int,int>(x,y));
				}
				else if(field[y][x-1]=='E'&&visited.find(std::pair<int,int>(x-1,y))==visited.end())
				{
					std::swap(field[y][x],field[y][x-1]);
					visited.insert(std::pair<int,int>(x,y));
				}
				else if(field[y+1][x]=='N'&&visited.find(std::pair<int,int>(x,y+1))==visited.end())
				{
					std::swap(field[y][x],field[y+1][x]);
					visited.insert(std::pair<int,int>(x,y));
				}
			}
			else if(field[y][x]=='X')
			{
				if(field[y][x+1]=='W'&&visited.find(std::pair<int,int>(x+1,y))==visited.end())
				{
					field[y][x+1]='.';
					remain--;
				}
				if(field[y-1][x]=='S'&&visited.find(std::pair<int,int>(x,y-1))==visited.end())
				{
					field[y-1][x]='.';
					remain--;
				}
				if(field[y][x-1]=='E'&&visited.find(std::pair<int,int>(x-1,y))==visited.end())
				{
					field[y][x-1]='.';
					remain--;
				}
				if(field[y+1][x]=='N'&&visited.find(std::pair<int,int>(x,y+1))==visited.end())
				{
					field[y+1][x]='.';
					remain--;
				}
			}
		}
	}
	return remain;
}