// [16 Oct 2005, by yuizumi]
// Fixed a bug that does not properly process the case containing no 'R's.

import java.io.*;

public class geometry_yuizumi {
	private static double compute(String line) {
		double xmax = 0.0;
		double ymax = 0.0;

		for(int i = 0; i < line.length(); i++) {
			if(line.charAt(i) == 'R') { xmax += 1.0; }
			if(line.charAt(i) == 'U') { ymax += 1.0; }
		}

		if(xmax == 0.0) return 0.0;

		double x = 0.0;
		double y = 0.0;
		double S = 0.0;

		for(int i = 0; i < line.length(); i++) {
			if(line.charAt(i) == 'R') {
				double xL = x + 0.0;
				double xR = x + 1.0;

				double yL = y * xmax - xL * ymax;
				double yR = y * xmax - xR * ymax;

				if(yL * yR < 0.0) {
					S += (yL * yL + yR * yR) / Math.abs(yL - yR);
				}
				else {
					S += Math.abs(yL + yR);
				}

				x += 1.0;
			}
			else {
				y += 1.0;
			}
		}

		return S / (2.0 * xmax);
	}

	public static void main(String[] args) throws Exception {
		BufferedReader br = null;
		try {
			br = new BufferedReader(new InputStreamReader(System.in));

			while(true) {
				String line = br.readLine();
				line = line.substring(0, line.length() - 1);
				if(line.length() == 0) { break; }
				System.out.println(compute(line));
			}
		}
		finally {
			if(br != null) br.close();
		}
	}
}