#include <stdio.h>

int main() {
    int month,day,cnt;
    float money;
    scanf("%f %d %d %d",&money,&month,&day,&cnt);
    if(month==11&&day==11)
    {
        money*=0.7;
    }
    else if(month==12&&day==12)
    {
        money*=0.8;
    }
    if(cnt==1)
    {
        if(money-50>=0)
         money-=50;
        else
         money=0;;
    }
    printf("%.2f",money);
}