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

using ll = long long;

int main(void) {
	string S;
	cin >> S;
	
	ll now = 1;
	for(auto c : S) {
		now *= 2;
		if(c == 'R') now += 1;
	}
	
	cout << now << "\n";
	
	return 0;
}