import java.util.Scanner;
import java.util.Stack;

public class Main {
	static int[][] numbers;
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		String S = in.next();
        int max = 0;
         for(int i =0; i< 3; i++)  {
          int prev = S.charAt(i);
          if(prev=='R'){
        	  int to =1;
              for(int j =i+1; j<3; j++)  {
                 if(prev!=S.charAt(j)) break;
                to++;
              }
              max = Math.max(max, to); 
          }
        	       			 		
         }
         System.out.println(max);     
	}
	
	
}
/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