What is the value printed by the following C program?

#include 
  int f(int * a, int n) {
    if (n <= 0) return 0;
    else if ( * a % 2 = = 0) return *a + f(a + 1, n - 1);
    else return *a - f(a + 1, n - 1);
  }
int main() {
  int a[] = {
    12,
    7,
    13,
    4,
    11,
    6
  };
  print f( % d, f(a, 6));
  return 0;
}