foo.c: In function 'isyun':
foo.c:4:24: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    4 |         if (x % 4 == 0 && x % 100 != 0 || x % 400 == 0)
      |             ~~~~~~~~~~~^~~~~~~~~~~~~~~
foo.c: In function 'main':
foo.c:13:28: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   13 |         if (month % 2 != 0 && month < 8 || month % 2 == 0 && month >= 8)
      |             ~~~~~~~~~~~~~~~^~~~~~~~~~~~

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