Objective

In this challenge, you will learn simple usage of functions in C. Functions are a bunch of statements grouped together. A function is provided with zero or more arguments, and it executes the statements on it. Based on the return type, it either returns nothing (void) or something.

A sample syntax for a function is

	return_type function_name(arg_type_1 arg_1, arg_type_2 arg_2, ...) {
    	...
        ...
        ...
        [if return_type is non void]
        	return something of type `return_type`;
    }

For example, a function to read four variables and return the sum of them can be written as

	int sum_of_four(int a, int b, int c, int d) {
    	int sum = 0;
        sum += a;
        sum += b;
        sum += c;
        sum += d;
        return sum;
    }

+= : Add and assignment operator. It adds the right operand to the left operand and assigns the result to the left operand.

a += b is equivalent to a = a + b;

Task

Write a function int max_of_four(int a, int b, int c, int d) which reads four arguments and returns the greatest of them.

Note

There is not built in max function in C. Code that will be reused is often put in a separate function, e.g. int max(x, y) that returns the greater of the two values.