import java.util.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
        Scanner sn = new Scanner(System.in);
        String str = sn.next();
        int cnt = 0;
        for ( int i = 0; i < 3; i++){
            String c = str.substring(i,i+1);
            if (c.equals("R")){
                cnt = cnt + 1;
            }
        }
        if ( str.equals("RSR")) {
                cnt = 1;
        }
        System.out.println(cnt);
    }
}

/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