import java.io.*;
import java.util.*;
import java.math.*;
import java.lang.*;
 
 //@Manan Parmar

public class Main implements Runnable {


    public void run() {
        
        InputReader sc = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);
 
        String s=sc.next();
        int r=0;
        if(s.charAt(0)=='R'&&(s.charAt(1)=='R'&&s.charAt(2)=='R'))
            r=3;
        else if((s.charAt(1)=='R'&&s.charAt(2)=='R'))
            r=2;
        else if(s.charAt(0)=='R'&&s.charAt(1)=='R')
            r=2;
        else if(s.charAt(0)=='R'||(s.charAt(1)=='R'||s.charAt(2)=='R'))
            r=1;
        out.println(r);
        out.close();
    }
 

//========================================================================

    static class Pair
    {
        int a,b;
        Pair(int aa,int bb)
        {
            a=aa;
            b=bb;
        }
    }
    static int smallestDivisor(int n)  
    {  
        // if divisible by 2  
        if (n % 2 == 0)  
            return 2;  
      
        // iterate from 3 to sqrt(n)  
        for (int i = 3; i * i <= n; i += 2) {  
            if (n % i == 0)  
                return i;  
        }  
      
        return n;  
    }  
    static void sa(int a[],InputReader sc)
    {
        for(int i=0;i<a.length;i++)
        {
            a[i]=sc.nextInt();
        }
        Arrays.sort(a);
    }

    static class PairSort implements Comparator<Pair>
    {
        public int compare(Pair a,Pair b)
        {
            return b.b-a.b;
        }
    }


    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;
        private BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 
        public InputReader(InputStream stream) {
            this.stream = stream;
        }
       
        public int read() {
            if (numChars==-1)
                throw new InputMismatchException();
           
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                }
                catch (IOException e) {
                    throw new InputMismatchException();
                }
               
                if(numChars <= 0)              
                    return -1;
            }
            return buf[curChar++];
        }
     
        public String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
        public int nextInt() {
            int c = read();
           
            while(isSpaceChar(c))
                c = read();
           
            int sgn = 1;
           
            if (c == '-') {
                sgn = -1;
                c = read();
            }
           
            int res = 0;
            do {
                if(c<'0'||c>'9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
           
            return res * sgn;
        }
       
        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
           
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
                return res * sgn;
        }
       
        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, nextInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }
       
        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));
           
            return res.toString();
        }
     
        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
     
        public String next() {
            return readString();
        }
       
        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }

    public static void main(String args[]) throws Exception {
        new Thread(null, new Main(),"Main",1<<27).start();
    }
}


Measured memory_bytes: 32852