/* Problem 5--Advanced Tic-Tac-Toe
   This was just a matter of counting the horizontal, vertical, and
   diagonal solutions. */

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

#define MIN(a,b) ((a)<(b)?(a):(b))

FILE *in, *out;

int main (int argc, char **argv);
int count (int r, int c, int k);

int main (int argc, char **argv) {

  int r, c, k;

 in = fopen ("prob5.in","r");
 out = fopen ("prob5.out","w");
 while (fscanf (in,"%d",&r),r>0) { /* Process input. */
  fscanf (in,"%d %d",&c,&k);
  fprintf (out,"%d\n",count (r,c,k));
 }
 fclose (in);
 fclose (out);
 return EXIT_SUCCESS;
}

/* returns total number of tic-tac-toe solutions for the various values
   of r, c, and k. */
int count (int r, int c, int k) {

  int total=0;

 if (k==1) return r*c; /* Special case; each square is a solution. */
 if (k <= r) total+= c*(r-k+1); /* Vertical solutions */
 if (k <= c) total+= r*(c-k+1); /* Horizontal solutions */
 if (k <= r && k <= c) /* Diagonal solutions */
  total += 2*(1+abs(r-c)+MIN(r,c)-k)*(MIN(r,c)-k+1);
 return total;
}