foo.cc: In function 'int main()':
foo.cc:42:9: warning: unused variable 'j' [-Wunused-variable]
   42 |  int i, j, k;
      |         ^
foo.cc:43:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   43 |  scanf("%d%d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~
foo.cc:52:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   52 |    scanf("%d%d", &a, &b);
      |    ~~~~~^~~~~~~~~~~~~~~~
foo.cc:57:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   57 |    scanf("%d", &a);
      |    ~~~~~^~~~~~~~~~

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