import java.util.Scanner;

public class Main {
    public static Scanner Scan = new Scanner(System.in);
    public static void main(String[] args) {
        String s;
        s = Scan.next();

        int cnt = 0, ans = 0;
        for(int i=0; i<s.length(); i++) {
            if(s.charAt(i) == 'R') cnt++;
            else cnt = 0;
            ans = Math.max(ans, cnt);
        }

        System.out.println(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