#include <bits/stdc++.h>

using namespace std;

#define REP(i,a,b) for(int i=a;i<(int)b;i++)
#define rep(i,n) REP(i,0,n)

int main() {
  
  string s; cin >> s;
  long long a = 1;
  rep(i, s.size()) {
    a = 2*a + (s[i] == 'R');
  }
  cout << a << endl;
  
  return 0;
}