Problem 2-2 price ladder (15 minutes)

To promote residents to conserve electricity, power companies performing province "price ladder", a mounting table of a residential user tariff is divided into two "step": Within months consumption 50 kwh (50 kWh) of price is 0.53 yuan / kWh; over 50 kwh, the excess portion of the electricity price increase 0.05 yuan / kWh. Write a program to calculate electricity.

Input formats:

Gives a user input in line with monthly consumption (unit: kWh).

Output formats:

Output line of the user tariff payable (RMB), the results of two decimals, formats such as: "cost = cope tariff value"; if power consumption is less than 0, then output "Invalid Value!".

Sample Input 1:

10

 

Output Sample 1:

cost = 5.30

 

Sample Input 2:

100

 

Output Sample 2:

cost = 55.50

#include<stdio.h>
int main(void)
{
    float a,Sum;
    scanf("%f",&a);
    if(a<0)
        printf("Invalid Value!");
    else if(a>=0&&a<=50){
        Sum=0.53*a;
        printf("cost = %.2f",Sum);
    }
    else{
        Sum=0.53*50+(0.53+0.05)*(a-50);
        printf("cost = %.2f",Sum);
    } 
        
    return 0;                        
}