import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String line = sc.nextLine();
    String data[] = line.split("");
    int count = 0;
    int n = 0;
    int flag = 0;
    int max = 0;
    while(n < data.length){
      if(data[n].equals("R")){
        count++;
        if(max < count){
          max = count;
        }
      }
      else{
        count = 0;
      }
      n++;
    }
    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