import java.util.*;

public class Main
{
  public static void main(String[] args)
  {
  	Scanner sc = new Scanner(System.in);
    String s = sc.next();

    int max = 0;
    int tmp = 0;

    for (int i=0; i<s.length(); i++)
    {
        if (s.charAt(i) == 'R')
            tmp++;
        else
            tmp = 0;
        
        if (tmp > max)
            max = tmp;
    }

    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