foo.cc: In function 'int main()':
foo.cc:13:29: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   13 |                 if(year%4==0&&year%100!=0||year%400==0)
      |                    ~~~~~~~~~^~~~~~~~~~~~~
foo.cc:18:15: warning: 'days' may be used uninitialized [-Wmaybe-uninitialized]
   18 |         cout<<days;
      |               ^~~~
foo.cc:5:25: note: 'days' was declared here
    5 |         int year,mounth,days;
      |                         ^~~~

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