import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		String str = sc.next();

		int count = 0;

		for(int i = 0; i < 3; i++) {


				if(count > 0) {
					if(str.charAt(i) == 'R') {
						if(str.charAt(i-1) == 'R') {
							count++;
						}
					}



			} else {
				if(str.charAt(i) == 'R') {
					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