foo.c: In function 'main':
foo.c:7:24: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    7 |         if (n % 4 == 0 && n % 100 != 0 || n % 400 == 0)
      |             ~~~~~~~~~~~^~~~~~~~~~~~~~~
foo.c:25:10: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
   25 |         }printf("%d", s);
      |          ^~~~~~~~~~~~~~~

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