import java.util.Scanner;
public class Main{
	public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
      	String S = sc.next();
      	String[] Rain = S.split("S");
      	
      	int max_r = 0;
      	for(String r : Rain){
        	if(max_r < r.length()){
            	max_r = r.length();
            }
        }
    System.out.println(max_r);
    }
}
/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