#include <cstdio>
#include <iostream>
using namespace std;

int main()
{
    int month,date,save;
    double price;
    cin>>price>>month>>date>>save;
    if(date==11&&month==11) price=0.7*price;
    else price=0.8*price;
    if(save==1&&(price-50>=0)) price=price-50;
    else if(save==1&&(price-50<=0)) price=0;
    printf("%.2lf",price);
    return 0;
    
}