/in/foo.c: In function 'main':
/in/foo.c:18:22: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   case 2:if(year%4==0&&year%100!=0||year%400==0)
             ~~~~~~~~~^~~~~~~~~~~~~
/in/foo.c:23:2: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  if(flag=1)
  ^~
/in/foo.c:24:3: warning: 'days' may be used uninitialized in this function [-Wmaybe-uninitialized]
   printf("%d\n",days);
   ^~~~~~~~~~~~~~~~~~~