import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
	    Scanner s = new Scanner(System.in);
	    String st = s.nextLine();
	    
	    int cnt = 0;
	    
	    for(int i = 0; i < st.length(); i++){
	    	
	     	if(st.charAt(i) == 'R')
	          cnt += 1;
	      	else
	          if(cnt != 0)
	            break;
	      
	    }  
	    
	    System.out.println(cnt);
	}

}
/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