#include<stdio.h>
struct order{
    int quantiity;
    float price_per_book;
    union{
        float discountRate;
        float discountPercent;
    }disc;
    float total_cost;
};
int main(){
    struct order order;
    order.price_per_book = 100.0f;
    scanf("%d",&order.quantity);
    if(order.quantity<0) {
        printf("Invalid input");
        return 0;
        }
        if(order.quantity>=1 && order.quantity<=5) {
            order.disc.diecountRate = 0.10f;
            }
            else if(order.quantity>=6 && order.quantity<=10)
            {
                order.dis.discountRate=0.15;
            }
            else if(order.quantity >10){
                order.disc.discountRate =0.20f;
            }
            else {
                order.disc.discountRate =0.0f;
            }
            float gross = order.quantity * order.price_per_book;
            order.total_cost = gross * (1.0f * order.disc.discountRate);
            printf("%.2f",order.total_cost);
            return 0;
}