import java.util.*;

public class Main{

    static int[] dp;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        char[] cs = s.toCharArray();
        dp = new int[3];
        
        dp[0] = (cs[0]=='R'?1:0);

        for(int i=1;i<3;i++){
            dp[i] = cs[i]=='R'?(dp[i-1]+1):0;
        }

        int max = 0;
        for (int i = 0; i < 3; i++) {
            max = Math.max(max, dp[i]);
        }

        System.out.println(max);

        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