#include <iostream>
#include <string>

void solve() {
    std::string s;
    std::cin >> s;

    int x = 1;
    for (char c : s) {
        x = x * 2 + (c == 'R');
    }
    std::cout << x << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::cout.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}