//problem no b
#include <stdio.h>

    int main()
    {
     int no_students,burger,candy,coke,total;
      double discount,amount;
     scanf("%d %d %d %d",&no_students,&burger,&candy,&coke);
     total=no_students*(burger+candy+coke);
     if(total>=5000&&total<=10000)
     {
         discount=total*.05;
         amount=total-discount;
         printf("%.2lf\n",amount);
     }
     else if(total>10000)
     {
         discount=total*.1;
         amount=total-discount;
         printf("%.2lf\n",amount);
     }
      return 0;
    }