Program should read the units consumed for a customer and calculate the total bill

Program:

#include<stdio.h>
#include<string.h>
#include<conio.h>
int main(){  
    int cust_no, unit_con;
    float charge,surcharge=0, amt,total_amt;
    char nm[25];   

    printf("\nEnter the customer Name :");
    scanf("%s",nm);

    printf("\nEnter the unit consumed by customer:");
    scanf("%d",&unit_con);

    if (unit_con <200 ){
        charge = 0.50;
        surcharge = 0;
        amt = unit_con*charge;
        total_amt = amt+surcharge;
    }
    elseif (unit_con>=200 && unit_con<400) {
        charge = 0.65;
        surcharge = 100;
        amt = unit_con*charge;
        total_amt = amt+surcharge;
    }
    else if (unit_con>=400 && unit_con<600){
        charge = 0.85;
        surcharge = 230;
        amt = unit_con*charge;
        total_amt = amt+surcharge;
    }
    else{
        charge = 1.00;
        surcharge = 390;
        amt = unit_con*charge;
        total_amt = amt+surcharge;
    }
    printf("\n\t\t\tElectricity Bill\n\n");
    printf("\nCustomer Name:\t%s",nm);
    printf("\nunit Consumed:\t%5d",unit_con);
printf("\nAmount Charges per unit:\t%8.2f",charge,amt);
printf("\nSurcharge Amount:\t%8.2f",surcharge);
printf("\nNet Amount Paid By the Customer:\t%8.2f",total_amt);
getch();
}//main ends

Output:

Enter the customer Name: DIEGO COSTA

Enter the unit consumed by customer: 420

Amount Charges per unit: 0.85

Surcharge Amount: 230