#include <bits/stdc++.h>
using namespace std;
string s, t;
double best[2005000][2];
int main() {
  ios_base::sync_with_stdio(0);
  int n;
  cin >> s;
  n = s.size();
  for (int i = 0; i < n; i++) {
    t += s[i];
    if (i + 1 < n && s[i] != 'X' && s[i] == s[i + 1]) t += 'X';
  }
  if (s[0] == s[n - 1] && s[0] != 'X') {
    if (s[0] == 'L')
      t += 'X';
    else
      t = "X" + t;
  }
  s = t;
  n = s.size();
  double lo = 0, hi = 1;
  while (hi - lo > 1e-10) {
    double mid = (lo + hi) / 2;
    best[0][0] = 0.0;
    best[0][1] = -mid;
    for (int i = 0; i < n; i++) {
      best[i + 1][0] = best[i][1] - mid;
      best[i + 1][1] = best[i][0] - mid;
      if (s[i] != 'X') {
        for (int k = 0; k < 2; k++) {
          if ((k == 0) ^ (s[i] == 'L')) {
            best[i + 1][k] = max(best[i + 1][k], best[i][k ^ 1] + 1 - mid);
          }
        }
      }
      best[i + 1][0] = max(best[i + 1][0], best[i + 1][1] - mid);
      best[i + 1][1] = max(best[i + 1][1], best[i + 1][0] - mid);
    }
    if (best[n][0] > 0) {
      lo = mid;
    } else {
      hi = mid;
    }
  }
  int x = 1e8 * (lo + 1e-10);
  printf("%d.%06d\n", x / 1000000, x % 1000000);
}
