#include <bits/stdc++.h>
using namespace std;
enum {X, N, E, S, W};
const int INF = 9999999;
int dir[128];
int v[505][505];
int dp[505][2];
inline int dist(int a, int b)
{
if(a == X) return INF;
return (a <= b ? b-a : b-a+4);
}
signed main()
{
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int n,m; cin>>n>>m;
char ch;
dir['N'] = N;
dir['E'] = E;
dir['S'] = S;
dir['W'] = W;
dir['X'] = X;
for(int i=1; i<=n; ++i)
for(int j=1; j<=m; ++j)
{
cin>>ch;
v[i][j] = dir[ch];
}
dp[1][0] = 0;
dp[1][1] = INF;
for(int i=1; i<m; ++i)
{
dp[i+1][0] = min(dp[i][0], dp[i][1] + dist(v[2][i], N)) + dist(v[1][i], E);
dp[i+1][1] = min(dp[i][1], dp[i][0] + dist(v[1][i], S)) + dist(v[2][i], E);
}
if(n == 1)
{
cout<<(dp[m][0] >= INF ? -1 : dp[m][0]);
}
else
{
int res = min(dp[m][1], dp[m][0] + dist(v[1][m], S));
cout<<(res >= INF ? -1 : res);
}
return 0;
}
