#include <stdio.h>
int main()
{
    int quantity;
    scanf("%d", &quantity);
    if (quantity < 0)
    {
        printf("Invalid input\n");
        return 0;
    }
    const float pricePerBook = 100.0;
    float discountRate = 0.0;
    if (quantity >= 1 && quantity <= 5)
    {
        discountRate = 0.10;
    }
    else if (quantity >= 6 && quantity <= 10)
    {
        discountRate = 0.15;
    }
    else if (quantity > 10)
    {
        discountRate = 0.20;
    }
    float totalCost = quantity * priceBook * (1 - discountRate);
    printf("%.2f\n", totalCost);
    return 0;
}