

import java.io.*;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
//        int t = in.nextInt();
        solver.solve(1, in, out);
        out.close();
    }

    static class Task {
        public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException {
            String s = in.next();
            int count = 0;
            for (int i = 0; i < s.length(); i++) {
                char ch = s.charAt(i);
                if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                }
            }
            out.println(count);
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public char nextChar() {
            return next().charAt(0);
        }

        public String nextLine() throws IOException {
            return reader.readLine().trim();
        }
    }
} import java.io.*; io.* java import java.util.StringTokenizer; StringTokenizer java.util public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
//        int t = in.nextInt();
        solver.solve(1, in, out);
        out.close();
    }

    static class Task {
        public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException {
            String s = in.next();
            int count = 0;
            for (int i = 0; i < s.length(); i++) {
                char ch = s.charAt(i);
                if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                }
            }
            out.println(count);
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public char nextChar() {
            return next().charAt(0);
        }

        public String nextLine() throws IOException {
            return reader.readLine().trim();
        }
    }
} Main public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
//        int t = in.nextInt();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
//        int t = in.nextInt();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out InputReader in = new InputReader(inputStream); in new InputReader(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) Task solver = new Task(); solver new Task() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class Task {
        public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException {
            String s = in.next();
            int count = 0;
            for (int i = 0; i < s.length(); i++) {
                char ch = s.charAt(i);
                if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                }
            }
            out.println(count);
        }
    } Task public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException {
            String s = in.next();
            int count = 0;
            for (int i = 0; i < s.length(); i++) {
                char ch = s.charAt(i);
                if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                }
            }
            out.println(count);
        } solve {
            String s = in.next();
            int count = 0;
            for (int i = 0; i < s.length(); i++) {
                char ch = s.charAt(i);
                if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                }
            }
            out.println(count);
        } String s = in.next(); s in.next() in.next in int count = 0; count 0 for (int i = 0; i < s.length(); i++) {
                char ch = s.charAt(i);
                if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                }
            } int i = 0; int i = 0; i 0 i < s.length() i s.length() s.length s i++ i++ i {
                char ch = s.charAt(i);
                if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                }
            } {
                char ch = s.charAt(i);
                if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                }
            } char ch = s.charAt(i); ch s.charAt(i) s.charAt s i if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                } ch == 'R' ch 'R' {
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                } count++ count if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    } i < s.length() - 1 && s.charAt(i+1) == 'S' i < s.length() - 1 i s.length() - 1 s.length() s.length s 1 s.charAt(i+1) == 'S' s.charAt(i+1) s.charAt s i+1 i 1 'S' {
                        break;
                    } break; out.println(count) out.println out count int testNumber testNumber InputReader in in PrintWriter out out static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public char nextChar() {
            return next().charAt(0);
        }

        public String nextLine() throws IOException {
            return reader.readLine().trim();
        }
    } InputReader public BufferedReader reader; reader public StringTokenizer tokenizer; tokenizer public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } InputReader {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } reader = new BufferedReader(new InputStreamReader(stream), 32768) reader new BufferedReader(new InputStreamReader(stream), 32768) tokenizer = null tokenizer null InputStream stream stream public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } next {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } IOException e {
                    throw new RuntimeException(e);
                } throw new RuntimeException(e); new RuntimeException(e) {
                    tokenizer = new StringTokenizer(reader.readLine());
                } tokenizer = new StringTokenizer(reader.readLine()) tokenizer new StringTokenizer(reader.readLine()) return tokenizer.nextToken(); tokenizer.nextToken() tokenizer.nextToken tokenizer public long nextLong() {
            return Long.parseLong(next());
        } nextLong {
            return Long.parseLong(next());
        } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next public double nextDouble() {
            return Double.parseDouble(next());
        } nextDouble {
            return Double.parseDouble(next());
        } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next public int nextInt() {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next public char nextChar() {
            return next().charAt(0);
        } nextChar {
            return next().charAt(0);
        } return next().charAt(0); next().charAt(0) next().charAt next() next 0 public String nextLine() throws IOException {
            return reader.readLine().trim();
        } nextLine {
            return reader.readLine().trim();
        } return reader.readLine().trim(); reader.readLine().trim() reader.readLine().trim reader.readLine() reader.readLine reader public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
//        int t = in.nextInt();
        solver.solve(1, in, out);
        out.close();
    }

    static class Task {
        public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException {
            String s = in.next();
            int count = 0;
            for (int i = 0; i < s.length(); i++) {
                char ch = s.charAt(i);
                if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                }
            }
            out.println(count);
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public char nextChar() {
            return next().charAt(0);
        }

        public String nextLine() throws IOException {
            return reader.readLine().trim();
        }
    }
} public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
//        int t = in.nextInt();
        solver.solve(1, in, out);
        out.close();
    }

    static class Task {
        public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException {
            String s = in.next();
            int count = 0;
            for (int i = 0; i < s.length(); i++) {
                char ch = s.charAt(i);
                if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                }
            }
            out.println(count);
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public char nextChar() {
            return next().charAt(0);
        }

        public String nextLine() throws IOException {
            return reader.readLine().trim();
        }
    }
} Main


import java.io.*;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
//        int t = in.nextInt();
        solver.solve(1, in, out);
        out.close();
    }

    static class Task {
        public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException {
            String s = in.next();
            int count = 0;
            for (int i = 0; i < s.length(); i++) {
                char ch = s.charAt(i);
                if (ch == 'R'){
                    count++;
                    if (i < s.length() - 1 && s.charAt(i+1) == 'S'){
                        break;
                    }
                }
            }
            out.println(count);
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public char nextChar() {
            return next().charAt(0);
        }

        public String nextLine() throws IOException {
            return reader.readLine().trim();
        }
    }
}
