#include<cstdio>
#include <iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>

using namespace std;
typedef long long ll;
typedef pair<int, int> Pr;

string s;

int main()
{
	cin >> s;
	int now = 1;
		for (int i = 0; i < s.size(); i++) {
			if (s[i] == 'R')now = 2 * now + 1;
			else now = 2 * now;
		}
		cout << now << endl;
	return 0;
}