import java.util.*;


import java.io.*;
/**
 * MLASERP
 */
public class Main {

    
    static MyScanner in  = new MyScanner();
   static int mod  = 1000000007;
    static PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      static StringTokenizer st;
      static int []dr  = {1,-1,0,0};
      static int [] dc = {0,0,-1,1};
public static void main(String[] args) {
    String s = in.next();
    int max =0;
    int n= s.length();
    int length =0;
    for(int i=0;i<n;i++){
        if(s.charAt(i)=='R'){
            int j= i;
            while(j<s.length()&&s.charAt(j)=='R'){
                length++;
                j++;
            }
            max = Math.max(length, max);
            length = 0;
        }
    }
    out.println(max);

   out.flush();
   

}
static int rcToxy(int r, int c,int W){
    return r*W+c;
}
static class Node{
    int r, c,prev,change;
    Node(int r, int c){
        this.r =r ;
        this.c = c;
    }
}
public static class MyScanner {
      BufferedReader br;
      StringTokenizer st;
 
      public MyScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      }
 
      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }
 
      int nextInt() {
          return Integer.parseInt(next());
      }
 
      long nextLong() {
          return Long.parseLong(next());
      }
 
      double nextDouble() {
          return Double.parseDouble(next());
      }
 
      String nextLine(){
          String str = "";
	  try {
	     str = br.readLine();
	  } catch (IOException e) {
	     e.printStackTrace();
	  }
	  return str;
      }

   }
}
/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