#include <stdio.h>
#include <stdlib.h>
#include <limits.h>

int calculate_d(int a, int b, int c)
{
	int d;
	if(a == b || c < b ) 
	{
		d = (a + b)/2;
	}
	else if(b == 1 || c)
	{
		d = a + c%2;
	}
	else
	{
		d = 2*b;
	}
	
	return d;
}

int main()
{
	int a, b, c;
	
	// a) 
	a = 6;    b = 5;    c = 8;    
	printf("a)  d=%d\n\n", calculate_d(a,b,c));
	
	// b) 
	a = 1;    b = 1;    c = 0;
	printf("b)  d=%d\n\n", calculate_d(a,b,c));

	// c)
	a = 0;    b = 2;    c = 4;
	printf("c)  d=%d\n\n", calculate_d(a,b,c));

	// d)
	a = 0;    b = 1;    c = 0;
	printf("d)  d=%d\n\n", calculate_d(a,b,c));

	// e)
	a = 1;    b = -1;    c = 0;
	printf("d)  d=%d\n\n", calculate_d(a,b,c));

	system("pause");
}