import java.util.*;
import java.lang.*;
public class Main
{
  public static void main(String args[])
  {
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    if(s.charAt(0)=='R' && s.charAt(1)=='R' && s.charAt(2)=='R')
      System.out.println(3);
    else if(s.charAt(1)=='R' && (s.charAt(0)=='R' || s.charAt(2)=='R'))
      System.out.println(2);
    else if(s.charAt(0)=='R' || s.charAt(1)=='R' || s.charAt(2)=='R')
      System.out.println(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