C++ program to calculate the electricity bill of consumed units by user

#include<iostream>
#include<conio.h>

int main(void)
{

    int units,cunits,punits;
    float bill;

    std::cout<<"Enter the current reading = ";
    std::cin>>cunits;
    std::cout<<"Enter the previous reading = ";
    std::cin>>punits;

    units = cunits - punits;

    if(units < 300)
        bill = 3.0*units;
    if(units > 300 && units <= 400)
        bill = ((3.5*units) + (units*0.5/100.0));
    if(units > 400 && units <= 500)
        bill = ((4.5*units) + (units*0.7/100.0));
    if(units > 500)
        bill = ((5.0*units) + (units*0.9/100.0));

    std::cout<<"The electricity bill is = "<<bill;

    return 0;
}

Enter the current reading = 600
Enter the previous reading = 295
The electricity bill is = 1069.025024