#include<bits/stdc++.h>
using namespace std;

int main(){
	string s;
	cin>>s;
	if(s=="SSS") cout<<0<<endl;
	else if(s=="RRR") cout<<3<<endl;
	else if(s=="RRS"||s=="SRR") cout<<2<<endl;
	else cout<<1<<endl;
	return 0;
} 