C - Sum until user exits

Q. Find sum of 2 numbers and repeat the program until user exit.

#include<stdio.h>
#include<conio.h>

void main()
{
    int a, b, c;
    char ch;
    clrscr();
    do{
        printf("Enter 2 numbers: ");
        scanf("%d%d",&a,&b);
        c=a+b;
        printf("Sum = %d",c);
        printf("\n\nDo u want to continue y\n :");
        ch = getche();
    }while(ch=='y' || ch=='Y');
}

Enter 2 numbers: 10
20
Sum = 30
Do u want to continue y\n :y

Enter 2 numbers: 15
25
Sum = 40
Do u want to continue y\n :n