Program to print electricity bill by unit

#include<stdio.h>
void main()
{
int unit1,unit2,cons,a;
printf("Enter last unit : ");
scanf("%d",&unit1);

printf("Enter curret unit : ");
scanf("%d",&unit2);
a=unit2-unit1;
if(a<100) {
cons=a*6;
printf("your electricity Bill payment is: %d Rs\n",cons);
}
else
if(a<200) {
cons=a*7 ;
printf("your electricity Bill payment is: %dRs\n",cons);
}
else
if (a<=300){
cons=a*8;
printf("your electricity Bill payment is: %d Rs \n",cons);
}
else
if(a>300) {
cons=a*10;
printf("your electricity Bill payment is: %d Rs \n",cons);
}
printf("current unit is : %d\n",a);
printf("Pay Now\n");

}

out put:-

Program to print electricity bill by unit