import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn=new Scanner(System.in);
		 String s =scn.next();
		 int ans=0;
		 if(s.charAt(0)=='R'){
			 ans=1;
			 if(s.charAt(1)=='R'){
				 ans++;
				 if(s.charAt(2)=='R'){
					 ans++;
				 }
			 }
			 
		 }else{
			 if(s.charAt(1)=='R'){
				 ans++;
				 if(s.charAt(2)=='R'){
					 ans++;
				 }
			 }else{
				 if(s.charAt(2)=='R'){
					 ans++;
				 }
			 }
		 }
		 System.out.println(ans);

	}

}
/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