import java.util.Scanner;

class Main{
    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        String str = sc.next();
        sc.close();

        if(str.equals("RRR")){
            System.out.println("3");
        }
        else if(str.contains("RR")){
            System.out.println("2");
        }
        else if(str.contains("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