#include <bits/stdc++.h>
#define pb push_back
#define int long long
using namespace std;
const int N=5e2+5;
char v[N][N];
int dir[N][N];
int dp[N][3];
signed main()
{
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
int n,m;
cin>>n>>m;
char ch;
for(int i=1;i<=n;++i) for(int j=1;j<=m;++j) cin>>v[j][i];
for(int i=1;i<=m;++i) for(int j=1;j<=n;++j)
{
if(v[i][j]=='X') continue;
if(v[i][j]=='N') dir[i][j]=0;
if(v[i][j]=='E') dir[i][j]=1;
if(v[i][j]=='S') dir[i][j]=2;
if(v[i][j]=='W') dir[i][j]=3;
}
//atentie la m=1!!!
for(int i=1;i<=m;++i) dp[i][1]=dp[i][2]=1e18;
dp[1][1]=0;
if(v[1][1]!='X') dp[1][2]=(2-dir[1][1]+4)%4;
for(int i=2;i<=m;++i)
{
if(v[i-1][1]!='X') dp[i][1]=min(dp[i][1],dp[i-1][1]+(1-dir[i-1][1]+4)%4);
if(v[i-1][2]!='X') dp[i][2]=min(dp[i][2],dp[i-1][2]+(1-dir[i-1][2]+4)%4);
int a=dp[i][1],b=dp[i][2];
if(v[i][2]!='X') dp[i][1]=min(dp[i][1],b+(0-dir[i][2]+4)%4);
if(v[i][1]!='X') dp[i][2]=min(dp[i][2],a+(2-dir[i][1]+4)%4);
}
cout<<(dp[m][2]==1e18 ? -1:dp[m][2]);
}
