#include <stdio.h>

double average(double a, double b);

int main() {
	
   double x = 2.437, y = -3.194; 
   double z = average(x, y);
   
          z = average(x);

   int    a = 2, b = -3; 
          z = average(a, b);
   int    c = average(x, y);

   average(x, y);
   
   average('a', 'b');
	
	return 0;
}

double average(double a, double b) {
	
	return (a + b) / 2;
}