#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ul;
typedef signed long long ll;

int main(void)
{
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);
  std::cout << std::fixed;
  string s;
  cin >> s;
  ll idx = 1;
  for (auto c : s) {
    idx *= 2;
    if (c=='R') idx++;
  }
  cout << idx << endl;
  return 0;
}