import java.util.Scanner;

public class Main 
{
    public static void main( String[] args )
    {
        try (Scanner scan = new Scanner(System.in)) {
            String input = scan.nextLine();
            int rain = 0, repeat = 0;
            for (char c : input.toCharArray()) {
                if (c == 'R') repeat++;
                else repeat = 0;
                if (rain < repeat) rain = repeat;
            }
            System.out.println(rain);
        }
    }
}
/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