import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    
    String s = sc.next();
    
    int cnt = 0;
    char[] c = s.toCharArray();
    if(c[0] == 'R' && c[1] == 'R' && c[2] == 'R') {
      cnt = 3;
    } else if(c[0] == 'R' && c[1] == 'R') {
      cnt = 2;
    } else if(c[1] == 'R' && c[2] == 'R') {
      cnt = 2;
    } else if(c[0] == 'R' || c[1] == 'R' || c[2] == 'R') {
      cnt = 1;
    }
    System.out.println(cnt);
  }
}
/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