#include<stdio.h>
 int main(){
    double price =  0;
    int month = 0;
    int day = 0;
    int flag = 0;
    double cut = 1.0;//折扣
    double last =0.0 ;
    scanf("%lf %d %d %d %d",&price,&month,&day,&flag);
    if(month==11 && day==11)
    {
        cut = 0.7;
        if(flag==1)
        {
            last = price*cut-50;
        }
        else
        {
            last = price*cut;
        }
    }
    else if(month==12 && day==12)
    {
        cut = 0.8;
        if(flag==1)
        {
            last = price*cut-50;
        }
        else
        {
            last = price*cut ;
        }
    }
    if(last<0.0)
    {
        printf("%.2lf\n",0.0);
    }
    else
    {
        printf("%.2lf\n",last);
    }
    return 0;
 }