import java.util.Scanner;

 
public class Main {
 
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		char[] s  = sc.nextLine().toCharArray();
		int ans = 0;
		int rain = 0;
		
		for(char c : s) {
			if(c == 'R') {
				rain++;
				if(ans < rain) {
					ans = rain;
				}
			}else {
				rain = 0;
			}
		}
		
		System.out.println(ans);
		sc.close();
	}
	
}



/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