/*
    /\_/\
   (= ._.)
   / >  \>
*/
#include <iostream>
#include <cstring>
#include <string>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <cstdio>
#include <cmath>
#include <cassert>
#define int long long
#define double long double
using namespace std;
const int N = 1010, M = 1e6 + 10, MOD = 1e9 + 7;
pair<int, int> a[N];
string s[N];
bool st[N];
double f[N][N];
void solve() {
	int n, m;
	cin >> n >> m;
	for (int i = 1; i <= n; i++) {
		cin >> s[i];
		s[i] = '#' + s[i];
	}
	for (int i = 0; i <= n; i++) {
		for (int j = 0; j <= m; j++) {
			f[i][j] = (double)(i * 10 + j * 10);
		}
	}
	double pi = 3.1415926535897;
	double d = 2.5 * pi;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			f[i][j] = min(f[i][j], min(f[i - 1][j - 1] + 20, min(f[i - 1][j] + 10, f[i][j - 1] + 10)));
//			if(s[i][j]=='O'){
//				f[i][j]=min()
//			}
			if (s[i][j] == 'O') f[i][j] = min(f[i][j], f[i - 1][j - 1] + 10 + d);
			if (s[i][j] == 'O' && s[i][j + 1] == 'O') {
				f[i][j + 1] = min(f[i][j + 1], f[i - 1][j - 1] + 10 + 2 * d);
				//f[i][j + 1] = min(f[i][j + 1], f[i][j] + d);
			}
			if (s[i][j] == 'O' && s[i + 1][j] == 'O') {
				f[i + 1][j] = min(f[i + 1][j], f[i - 1][j - 1] + 10 + 2 * d);
				//f[i + 1][j] = min(f[i + 1][j], f[i][j] + d);
			}

//			if (s[i - 1][j] == 'O' && s[i][j] == 'O') {
//				f[i][j] = min(f[i][j], f[i - 1][j] + d);
//			}
//			if (s[i][j - 1] == 'O' && s[i][j] == 'O') {
//				f[i][j] = min(f[i][j], f[i][j - 1] + d);
//			}
			//printf("%.10Lf ", f[i][j]);
		}
		//cout << '\n';
	}
	printf("%.10Lf", f[n][m]);
}
signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int TT = 1;
	//cin >> TT;
	while (TT--) {
		solve();
	}
	return 0;
}
/*
    /\_/\
   (= ._.)
   / >  \>
*/