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

const int N=707;
const double EPS=1e-9;
const double pi=acos(-1);
const double INF=1e18;
int n,m;
string s[N];
vector<pair<int,double>> g[N*N*4];
double dist[N*N*4];
bool vis[N*N*4];
signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    cout.precision(15);
    for (int i=0;i<N*N*4;++i) dist[i]=INF;
    cin>>n>>m;
    for (int i=0;i<n;++i) cin>>s[i];
    auto to_idx=[&](int x,int y){
        return x*(2*m+1)+y;
    };
    for (int i=0;i<=2*n;++i){
        for (int j=0;j<=2*m;++j){
            int x=to_idx(i,j), y=to_idx(i,j+1), z=to_idx(i+1,j);
            if (j<2*m&&(i%2==0)) g[x].push_back({y,5}), g[y].push_back({x,5});
            if (i<2*n&&(j%2==0)) g[x].push_back({z,5}), g[z].push_back({x,5});
        }
    }
    for (int i=0;i<n;++i){
        for (int j=0;j<m;++j){
            if (s[i][j]=='O'){
                int a[]={to_idx(2*i+1,2*j), to_idx(2*i,2*j+1), to_idx(2*i+1,2*j+2), to_idx(2*i+2,2*j+1)};
                for (int k=0;k<4;++k) g[a[k]].push_back({a[(k+1)%4],2.5*pi}), g[a[(k+1)%4]].push_back({a[k],2.5*pi});
            }
        }
    }
    priority_queue<pair<double,int>,vector<pair<double,int>>,greater<pair<double,int>>> pq;
    pq.push({0,0});
    dist[0]=0;
    while (pq.size()){
        auto ret=pq.top();
        pq.pop();
        if (vis[ret.second]) continue;
        vis[ret.second]=1;
        for (auto [x,y]:g[ret.second]){
            if (dist[x]>dist[ret.second]+y) dist[x]=dist[ret.second]+y, pq.push({dist[x],x});
        }
   }
   cout<<dist[to_idx(2*n,2*m)];
}