import java.io.IOException;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		sc.close();

		int max = 0;
		int temp = 0;
		for(int i=0; i < str.length(); i++) {
			char c = str.charAt(i);
			if(c == 'R'){
				temp++;
			} else {
				if(max < temp){
					max = temp;
					temp = 0;
				}
			}
		}
		if(max < temp){
			max = temp;
		}
		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