/in/foo.cc: In function 'int main()':
/in/foo.cc:6:11: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if(n%4==0&&n%100!=0||n%400!=0)
     ~~~~~~^~~~~~~~~~
/in/foo.cc:6:8: warning: 'n' is used uninitialized in this function [-Wuninitialized]
  if(n%4==0&&n%100!=0||n%400!=0)
     ~~~^~~