import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        String a = s.nextLine();
        int count = 0;

        if (a.equals("RRR"))
            count = 3;
        if (a.equals("RRS"))
            count = 2;
        if (a.equals("RSS"))
            count = 1;
        if (a.equals("SSS"))
            count = 0;
        if (a.equals("SSR"))
            count = 1;
        if (a.equals("SRR"))
            count = 2;
        if (a.equals("SRS"))
            count = 1;
        if (a.equals("RSR"))
            count = 1;

        System.out.println(count);

        s.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