foo.c: In function 'days_date':
foo.c:3:30: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    3 | #define leapYear(y) ((y%4==0)&&(y%100!=0)||(y%400==0))
      |                      ~~~~~~~~^~~~~~~~~~~~
foo.c:16:21: note: in expansion of macro 'leapYear'
   16 |                 if (leapYear(i))
      |                     ^~~~~~~~
foo.c:3:30: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    3 | #define leapYear(y) ((y%4==0)&&(y%100!=0)||(y%400==0))
      |                      ~~~~~~~~^~~~~~~~~~~~
foo.c:21:21: note: in expansion of macro 'leapYear'
   21 |                 if (leapYear(i))
      |                     ^~~~~~~~
foo.c: In function 'diff':
foo.c:32:16: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration]
   32 |         return abs(days_date(s1) - days_date(s2));
      |                ^~~
foo.c:3:1: note: include '<stdlib.h>' or provide a declaration of 'abs'
    2 | #include <math.h>
  +++ |+#include <stdlib.h>
    3 | #define leapYear(y) ((y%4==0)&&(y%100!=0)||(y%400==0))

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