import java.util.*;
class Main {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        String s=sc.next();
        int count=0;
        int max=Integer.MIN_VALUE;
        if(s.charAt(0)=='R' && s.charAt(1)=='R' && s.charAt(2)=='R')
        count=3;
        else if(s.charAt(0)=='R' && s.charAt(1)=='R')
        count=2;
        else if(s.charAt(1)=='R' && s.charAt(2)=='R')
        count=2;
        else if(s.charAt(0)!='R' && s.charAt(1)!='R' && s.charAt(2)!='R')
        count=0;
        else
        count=1;
        System.out.println(count);
    }    
}
/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