#include <bits/stdc++.h>
using namespace std;

typedef double db;
const db pi=acos(-1);
const db INF=1e18;

const int maxn=700;
const int N=700*700*10;

int n,m;
int a[maxn+50][maxn+50];

vector<pair<int,db> > g[N+50];
db dis[N+50];
//bool vis[N+50];

int getid(int i,int j){
	return i*(2*m+1)+j;	
}
void addedge(int u,int v,db w){
	g[u].emplace_back(v,w);
	g[v].emplace_back(u,w);
}

int main(){
	ios_base::sync_with_stdio(false);
	cin >> n >> m;
	for (int i=0;i<n;i++){
		string str;
		cin >> str;
		for (int j=0;j<m;j++) if (str[j]=='O') a[i][j]=1;
	}
	for (int i=0;i<n;i++){
		for (int j=0;j<m;j++){
			addedge(getid(2*i,2*j),getid(2*i,2*j+1),5);
			addedge(getid(2*i,2*j+1),getid(2*i,2*j+2),5);
			
			addedge(getid(2*i,2*j),getid(2*i+1,2*j),5);
			addedge(getid(2*i+1,2*j),getid(2*i+2,2*j),5);
			
			addedge(getid(2*i+2,2*j),getid(2*i+2,2*j+1),5);
			addedge(getid(2*i+2,2*j+1),getid(2*i+2,2*j+2),5);
			
			addedge(getid(2*i,2*j+2),getid(2*i+1,2*j+2),5);
			addedge(getid(2*i+1,2*j+2),getid(2*i+2,2*j+2),5);
			
			if (a[i][j]){
				addedge(getid(2*i,2*j+1),getid(2*i+1,2*j),5*pi/2);
				addedge(getid(2*i,2*j+1),getid(2*i+1,2*j+2),5*pi/2);
					
				addedge(getid(2*i+1,2*j),getid(2*i+2,2*j+1),5*pi/2);
				addedge(getid(2*i+1,2*j+2),getid(2*i+2,2*j+1),5*pi/2);	
			}
			for (int x=0;x<=2;x++){
				for (int y=0;y<=2;y++){
					dis[getid(2*i+x,2*j+y)]=INF;
				}
			}
		}
	}
	priority_queue<pair<db,int>,vector<pair<db,int>>,greater<pair<db,int>>> q;
	dis[getid(0,0)]=0;
	q.emplace(dis[getid(0,0)],getid(0,0));
//	vis[get(0,0)]=1;
	
	while (!q.empty()){
		auto qf=q.top();
		q.pop();
		int u=qf.second;
		db disu=qf.first;
		if (disu!=dis[u]) continue;
		for (auto [v,w]:g[u]){
		//	if (vis[v]) continue;
			if (disu+w<dis[v]){
				dis[v]=disu+w;
				q.emplace(dis[v],v);
		//		vis[v]=1;
			}
		}	
	}
	cout << fixed << setprecision(12) << dis[getid(2*(n-1)+2,2*(m-1)+2)] << "\n";
	return 0;
}