/*
    /\_/\
   (= ._.)
   / >  \>
*/
#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][3];
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][0] = (double)(i * 10 + j * 10);
			f[i][j][1] = (double)(i * 10 - 5 + j * 10);
			f[i][j][2] = (double)(i * 10 + j * 10 - 5);
		}
	}
	double pi = 3.1415926535897;
	double d = 2.5 * pi, t = 5;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			f[i][j][1] = min(f[i][j][1], f[i - 1][j][0] + t);
			f[i][j][2] = min(f[i][j][2], f[i][j - 1][0] + t);
			if (s[i][j] == 'O') {
				f[i][j][1] = min(f[i][j][1], f[i - 1][j - 1][0] + t + d);
				f[i][j][2] = min(f[i][j][2], f[i - 1][j - 1][0] + t + d);
			}
			if (s[i][j] == 'O' && s[i + 1][j] == 'O') {
				f[i + 1][j][1] = min(f[i + 1][j][1], f[i - 1][j - 1][0] + t + 2 * d);
				f[i + 1][j][2] = min(f[i + 1][j][2], f[i - 1][j - 1][0] + t * 3 + d);
			}
			if (s[i][j] == 'O' && s[i][j + 1] == 'O') {
				f[i][j + 1][1] = min(f[i][j + 1][1], f[i - 1][j - 1][0] + t * 3 + d);
				f[i][j + 1][2] = min(f[i][j + 1][2], f[i - 1][j - 1][0] + t + 2 * d);
			}
			f[i][j][0] = min(f[i][j][0], min(f[i][j][1], f[i][j][2]) + t);
		}
	}
	printf("%.10Lf", f[n][m][0]);
}
signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int TT = 1;
	//cin >> TT;
	while (TT--) {
		solve();
	}
	return 0;
}
/*
    /\_/\
   (= ._.)
   / >  \>
*/