No Argument but Returning type function

#include<stdio.h>
#include<conio.h>
int add();
void main()
{
int m;
clrscr();
m=add();
printf("The sum is : %d",m);
getch();
}
int add()
{
int a,b,s=0;
printf("Enter the number: ");
scanf("%d %d",&a,&b);
s=a+b;
return s;
}