import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String s = sc.nextLine();
    int ans = 0;
    if (s.equals("SSS"))
      ans = 0;
    if (s.equals("SSR"))
      ans = 1;
    if (s.equals("SRS"))
      ans = 1;
    if (s.equals("SRR"))
      ans = 2;
    if (s.equals("RSS"))
      ans = 1;
    if (s.equals("RSR"))
      ans = 1;
    if (s.equals("RRS"))
      ans = 2;
    if (s.equals("RRR"))
      ans = 3;
    System.out.println(ans);
    sc.close();
  }
}
/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