import java.security.SecureRandom;
import java.sql.Array;
import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s = sc.next();

        int count = 0;
//       if (s.charAt(0)=='R')count++;
//       else count=0;
//       if (s.charAt(1)=='R')count++;
//       else count=0;
//        if (s.charAt(2)=='R')count++;
//        else count=0;
        int max = Integer.MIN_VALUE;
        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) == 'R') count++;
            else count = 0;
            if (count > max) max = count;
        }

            System.out.println(max);

    }
    }

/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