import java.util.Scanner;
 
class Main {
  public static void main(String args[]) {
    Scanner sc = new Scanner(System.in);
    String s = sc.nextLine();
    int ans = 0;
    int i = 0;
    if(s.charAt(i) == 'R'){
      ans++;
      if(s.charAt(i + 1) == 'R'){
        ans++;
        if(s.charAt(i + 2) == 'R'){
        	ans++;
          
        }
      }
    }else if(s.charAt(i + 1) == 'R'){
      ans++;
      if(s.charAt(i + 2) == 'R'){
        ans++;
        
      }
    }else{
      if(s.charAt(i + 2) == 'R'){
        ans++;
        
      }
    }
  
System.out.print(ans);
  }
}
/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