foo.cc: In function 'int year(int)':
foo.cc:9:17: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    9 |  if (y % 4 == 0 && y % 100 != 0 || y % 400 == 0) i = 1;
      |      ~~~~~~~~~~~^~~~~~~~~~~~~~~
foo.cc: In function 'int fn(int, int, int, int)':
foo.cc:51:7: warning: statement has no effect [-Wunused-value]
   51 |  for (small; small <= big; small++)
      |       ^~~~~
foo.cc: In function 'int main()':
foo.cc:73:8: warning: ignoring return value of 'int system(const char*)', declared with attribute warn_unused_result [-Wunused-result]
   73 |  system("pause");
      |  ~~~~~~^~~~~~~~~

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