import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 文字列の入力
		String s = sc.next();
		// 出力
		if(s.indexOf("RRR") != -1){
		    System.out.println(3);
		}
		else if(s.indexOf("RR") != -1){
		    System.out.println(2);
		}
		else if(s.indexOf("R") != -1){
		    System.out.println(1);
		}
		else{
		    System.out.println(0);
		}
	}
}
/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