#include <bits/stdc++.h>

const double pi = acos(-1);
const double EPS = 1e-9;
const int N = 1405;
using pid = std::pair<int, double>;

int n, m;
char map[N][N];

std::vector<pid> rg[N];
int id[N][N], tot;

double dp[N * N];
double solve(int x) {
  if (x == 1) return 0;
  if (dp[x] > EPS) return dp[x];
  dp[x] = 1e18;

  for (auto [y, w] : rg[x])
    dp[x] = std::min(dp[x], solve(y) + w);
  return dp[x];
}

int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++)
    scanf("%s", map[i] + 1);
  
  for (int i = 0; i <= 2 * n; i++)
    for (int j = 0; j <= 2 * m; j++) {
      id[i][j] = ++tot;
      if (i && j % 2 == 0) rg[id[i][j]].emplace_back(id[i - 1][j], 5);
      if (j && i % 2 == 0) rg[id[i][j]].emplace_back(id[i][j - 1], 5);
    }
  
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      if (map[i][j] == 'X') continue;

      rg[id[2 * i - 1][2 * j]].emplace_back(id[2 * i - 2][2 * j - 1], 2.5 * pi);
      rg[id[2 * i][2 * j - 1]].emplace_back(id[2 * i - 1][2 * j - 2], 2.5 * pi);
    }
  }

  printf("%.10f", solve(id[n * 2][m * 2]));
  return 0;
}