Function IN C & CPP

 //Take Nothing Return Nothing

#include<stdio.h>
void sum()
{
    add();
}
void sum(void);// Function Declaration
void main()
{
    sum();// Function Call
}
void add()// Function Defination
{
    int a,b;
    printf("Enter Two Number");
    scanf("%d%d",&a,&b);
    printf("Sum is %d",a+b);
}