#include <bits/stdc++.h>   using namespace std;   int main() {     ios::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     long long n, p, b = 0;     cin >> n >> p;     vector<long long> v;     for (int i = 0; i < n; ++i) {       string s;       cin >> s;       if (s ==  half ) {         v.push_back(0);       } else         v.push_back(1), b++;     }     reverse(v.begin(), v.end());     long long at = 0;     for (int i = 0; i < n; ++i) {       at *= 2;       at += v[i];     }     cout << (at * p) - (b * p / 2) << endl;     return 0;   }   