foo.c: In function 'main':
foo.c:42:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   42 |     scanf("%d", &n);
      |     ^~~~~~~~~~~~~~~
foo.c:45:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   45 |         scanf("%d %d", &a[i], &b[i]);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.c:52:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   52 |         scanf("%d %d", &a[j], &b[j]); /* a[]分子，b[]分母 */
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

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