How to write a simple C program showing addition ?

$cat add-p1.c
#include <stdio.h>
#include <stdlib.h>

int add (int a,int b) {
return a + b;
}

int main() {
int a,b;
a =3;
b =4;
int ret = add(a,b);
printf("Result: %u\n",ret);
exit(0);
}

$gcc add-p1.c
$./a.out
Result: 7
$