#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template <typename T>
using indexed_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
static mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define ll long long
#define pb push_back
#define ppb pop_back
#define pf push_front
#define ppf pop_front
#define eb emplace_back
#define F fist
#define S second
constexpr int MAXN = 1e5;
const int LOG = __lg(MAXN)+1;
constexpr int INF = 1e9;
constexpr int MOD = 1e9+7;
constexpr double EPS = 1e-8;
/*
EJOI 2019, Day 2, problem A, 22p.
*/
int f(char c){
if (c == 'S'){
return 0;
} else if (c == 'E'){
return 1;
} else if(c == 'N'){
return 2;
} else{
return 3;
}
}
void solve(){
int n, m;
cin >> n >> m;
vector<string> grid(n);
for(auto& x: grid){
cin >> x;
}
int res = 0;
for(int i = 0; i + 1 < n; i++){
if (grid[i][0] == 'X'){
cout << "-1\n";
return;
}
res += f(grid[i][0]);
}
cout << res << '\n';
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int t = 1;
// cin >> t;
for(int i = 1; i <= t; i++){
solve();
}
}
