foo.c: In function 'mul':
foo.c:9:6: warning: unused variable 'i' [-Wunused-variable]
  int i, j;
      ^
foo.c: In function 'main':
foo.c:33:2: error: expected declaration or statement at end of input
  return 0;
  ^~~~~~
foo.c:28:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &x, &n);
  ^~~~~~~~~~~~~~~~~~~~~~

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