import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		String S = scan.next();

		int total = 0;

		String S1 = S.substring(0,1);
		String S2 = S.substring(1,2);
		String S3 = S.substring(2,3);

		int count = 0;
		while(count < 1)
		{
			if((S1 + S2 + S3).equals("RRR"))
			{
				total += 3;
				break;
			}

			if((S1 + S2).equals("RR") || (S2 + S3).equals("RR"))
			{
				total += 2;
				break;
			}

			if(S1.equals("R") || S2.equals("R") || S3.equals("R"))
			{
				total += 1;
				break;
			}
			count++;
		}

		System.out.println(total);

		scan.close();
	}
}

/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