这个c程序如果输入20的话，是不是只执行最后一个else后面的语句？？？

// Exercise 3.3 Calculate a discounted price
// I interpreted this exercise as implying that the 10% applies to items 31 to 50
// and the 15% applies to items in excess of 50.
// That is, you don't get 15% discount on the whole price when you order 51 items.
// There is more than one way of doing this so different is not necessarily wrong.
#include
int main(void)
{
const int level1 = 30; // Quantity over this level are at discount1
const int level2 = 50; // Quantity over this level are at discount2
const double discount1 = 0.10; // 10% discount
const double discount2 = 0.15; // 15% discount
const double unit_price = 5.0; // Basic unit price
int quantity = 0;
int qty_full_price = 0; // 0 to 30 at full price
int qty_level1 = 0; // 31 to 50 at level1 price
int qty_level2 = 0; // Over 50 at level2 price
printf("Enter the quantity that you require: ");
scanf("%d", &quantity);
if(quantity > 50) // Quantity over 50
{
qty_full_price = level1;
qty_level1 = level2 - level1;
qty_level2 = quantity - level2;
}
else if(quantity > 30) // Quantity is from 30 to 50
{
qty_full_price = level1;
qty_level1 = quantity - level1;
}
else
qty_full_price = quantity;
printf("The total price for %d items is $%.2lf\n", quantity,
unit_price*(qty_full_price + (1.0 - discount1)*qty_level1 + (1.0 - discount2)*qty_level2));
return 0;
}