import java.util.*;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		String s = sc.next();
		char[] S = s.toCharArray();

		int c = 0;
		boolean rain = false;
		for (int i = 0; i<2; i++) {
			if (S[i] == S[i+1] && S[i] == 'R') {
				c++;

			}
		}
		for (int i = 0; i<3;i++) {
			if (S[i] == 'R') {
				rain = true;
			}
		}
		if (rain) {
			System.out.println(c+1);
		} else {
			System.out.println(0);
		}
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz