import java.io.IOException;

public class Main {

	public static void main(String[] args) throws IOException {
		int count = 0;
		int res = 0;
		for (int i = 0; i < 3; i++) {
			char data = (char) System.in.read();
			if (data == 'R') {
				count++;
			}
			if (data == 'S') {
				count = 0;
			}
			if (count > res) {
				res = count;
			}
		}
		System.out.println(res);
	}

}

/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