View Compilation Error

0_0_13761800_7979.c: In function 'points':
0_0_13761800_7979.c:8:13: error: 'K' undeclared (first use in this function)
             K[k][0]  = pIPoint[j][0] - pIPoint[i][0];
             ^
0_0_13761800_7979.c:8:13: note: each undeclared identifier is reported only once for each function it appears in
0_0_13761800_7979.c:12:41: error: 'cmp' undeclared (first use in this function)
         qsort (K, k, sizeof (int) << 1, cmp);
                                         ^
0_0_13761800_7979.c: In function 'main':
0_0_13761800_7979.c:28:12: error: 'EOF' undeclared (first use in this function)
     while (EOF != scanf ("%d", &n)) {
            ^
0_0_13761800_7979.c:30:29: error: 'PS' undeclared (first use in this function)
             scanf ("%d%d", &PS[i][0], &PS[i][1]);
                             ^