#include<bits/stdc++.h>
using namespace std;
long long n,p,ans=0,total=0,apple=0;
int main()
{
    string a[100000];
    cin>>n>>p;
    p=p>>1;
    for(int i=1;i<=n;i++)
    {
    cin>>a[i];
}
for(int i=n;i>=1;i--)
{
    total=total*2;
    if(a[i]=="halfplus")
        total++;
    apple+=total;
    }
    cout<<apple*p;
    return 0;
}