#include<bits/stdc++.h>
#define inf 1e9
#define eps 1e - 6
#define FOR(i, a, b) for(int i = a;i <= b;i ++)
#define REP(i, a, b) for(int i = a;i >= b;i --)
#define pa pair<int, int>
#define fr first
#define sd second
#define pb push_back
#define db double
#define MEM(a) memset(a, 0, sizeof(a))
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
inline ll read()
{
	char ch = getchar();
	ll s = 0, w = 1;
	while (ch < '0' || ch > '9') {if (ch == '-')w = -1; ch = getchar();}
	while (ch >= '0' && ch <= '9') {s = s * 10 + ch - '0'; ch = getchar();}
	return s * w;
}
#define N 710
int n, m;
db dp[N][N][9];
const db pi = acos(-1.0);
db w1 = 2.5 * pi, w2 = 5.0;
char s[N];
int b[N][N];
vector w(9, vector<db>(9, 0));
vector g(9, vector<db>(9, 0));
inline void cmin(db &x, db y) {x = min(x, y);}
inline void calc(int x, int y)
{
	int T = 8;
	vector<int>vst(9, 0);
	while (T--)
	{
		db minn = inf; int mx = 0;
		FOR(i, 1, 8)if (dp[x][y][i] < minn && (!vst[i]))minn = dp[x][y][i], mx = i;
		vst[mx] = 1;
		FOR(j, 1, 8)cmin(dp[x][y][j], dp[x][y][mx] + (b[x][y] ? w[mx][j] : g[mx][j]));
	}
}
int main()
{
	FOR(i, 1, 8)FOR(j, 1, 8)w[i][j] = g[i][j] = inf;
	w[1][5] = w[5][2] = w[2][8] = w[8][4] = w[4][7] = w[7][3] = w[3][6] = w[6][1] = w2;
	w[1][6] = w[6][3] = w[3][7] = w[7][4] = w[4][8] = w[8][2] = w[2][5] = w[5][1] = w2;
	g = w;
	w[5][8] = w[8][7] = w[7][6] = w[6][5] = w1;
	w[5][6] = w[6][7] = w[7][8] = w[8][5] = w1;
	n = read(), m = read();
	FOR(i, 1, n)
	{
		scanf("%s", s + 1);
		FOR(j, 1, m)if (s[j] == 'O')b[i][j] = 1; else b[i][j] = 0;
	}
	FOR(i, 0, n)FOR(j, 0, m)FOR(k, 1, 8)dp[i][j][k] = inf;
	dp[1][1][1] = 0;
	FOR(i, 1, n)FOR(j, 1, m)
	{
		cmin(dp[i][j][1], dp[i - 1][j - 1][4]);
		cmin(dp[i][j][1], dp[i - 1][j][3]);
		cmin(dp[i][j][1], dp[i][j - 1][2]);

		cmin(dp[i][j][5], dp[i - 1][j][7]);
		cmin(dp[i][j][2], dp[i - 1][j][4]);

		cmin(dp[i][j][6], dp[i][j - 1][8]);
		cmin(dp[i][j][3], dp[i][j - 1][4]);
		calc(i, j);
	}
	printf("%.20lf\n", dp[n][m][4]);
	return 0;
}