foo.cc: In member function 'int Date::isLeap()':
foo.cc:34:18: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   34 |   if (y % 4 == 0 && y % 100 != 0 || y % 400 == 0)
      |       ~~~~~~~~~~~^~~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:89:15: warning: unused variable 'ad' [-Wunused-variable]
   89 |  int y, m, d, ad;
      |               ^~

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