#include<bits/stdc++.h>
#define rep(i,a,n) for (int i = a;i < n;i++)
#define per(i,n,a) for (int i = n-1;i >= a;i--)
using namespace std;

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