/in/foo.c: In function 'isleap_year':
/in/foo.c:6:20: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0)
      ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/in/foo.c: In function 'convert':
/in/foo.c:18:1: error: expected expression before '}' token
 }
 ^
/in/foo.c:18:1: error: expected expression before '}' token
/in/foo.c:13:6: warning: variable 'localmon' set but not used [-Wunused-but-set-variable]
  int localmon[12];
      ^~~~~~~~
/in/foo.c: In function 'main':
/in/foo.c:24:6: warning: unused variable 'day' [-Wunused-variable]
  int day = 3;
      ^~~
/in/foo.c:23:6: warning: unused variable 'date_after' [-Wunused-variable]
  int date_after[3];
      ^~~~~~~~~~
/in/foo.c:22:9: warning: unused variable 'date_before' [-Wunused-variable]
     int date_before[3] = {2019,12,30};
         ^~~~~~~~~~~