foo.c: In function 'PrimeCount':
foo.c:22:9: warning: unused variable 'j' [-Wunused-variable]
   22 |  int i, j, k = 0;
      |         ^
foo.c: In function 'main':
foo.c:37:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   37 |  scanf("%d %d", &n1, &n2);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~
foo.c:40:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   40 |   scanf("%d", &a[i]);
      |   ^~~~~~~~~~~~~~~~~~
foo.c:43:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   43 |   scanf("%d", &b[i]);
      |   ^~~~~~~~~~~~~~~~~~

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