#include <stdio.h>

int main(void)
{
    const int price = 5;
    unsigned int quantity = 0; 
    double total_price = 0;
    
    printf("Enter quantity:");
    scanf("%d", &quantity);
    
    total_price = quantity * (price * (quantity > 30 ? 0.9 : 
                  quantity > 50 ? 0.85 : 1)); 

    printf("%.2lf", total_price);  
    
    return 0;
}