
import java.util.*;

public class Main {

	public static void main(String args[])
	{
		Scanner sc=new Scanner(System.in);
		String st=sc.next();
		int max=0;
		for(int i=0;i<3;i++)
		{
			int j=i,count=0;
			while(j<3&&st.charAt(j)=='R') 
				{
					count++;
					j++;
				}
			max=Math.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