import java.util.Scanner;

public class Main{

    public static void main(String[] args) {
        Scanner std = new Scanner(System.in);
        String str = std.next();
        int count = 0;
        for(int i = 0; i < str.length(); i++) {
            if(count == 0 && 'R' == (char)str.charAt(i))
                count++;
            if(i > 0 && str.charAt(i - 1) == str.charAt(i) && 'R' == (char)str.charAt(i))
                count++;
        }

        System.out.println(count);
    }

}
/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