foo.c: In function 'main':
foo.c:22:11: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration]
   22 |    cnt += abs(a[i] - a[j]);
      |           ^~~
foo.c:15:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   15 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
foo.c:17:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   17 |   scanf("%d", &a[i]);
      |   ^~~~~~~~~~~~~~~~~~
foo.c:5:6: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
    5 |  int end = a[0];
      |      ^~~

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