import java.util.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    if (s.equals("RRR")) {
      System.out.println("3");
    } else if (s.equals("RRS") || s.equals("SRR")) {
      System.out.println("2");
    } else if (s.equals("RSS") || s.equals("SRS") || s.equals("SSR") || s.equals("RSR")) {
      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