Program To Calculate Customers Telephone Bill

#include<stdio.h>
void main()
{
int units, custno;
float charge;
clrscr();
printf("Enter customer number and unit consumed\n");
scanf("%d%d",&custno,&units);
if(units<=200)
charge=0.5*units;
else if(units<=400)
charge=100+0.25*(units-200);
else if(units<=600)
charge=230+0.8*(units-400);
else
charge=390+(units-600);
printf("Customer no:%d consumed :%d units\n",custno,units);
printf("Total bill amount is : %.2f\n",charge);
}