foo.cc: In function 'int main()':
foo.cc:49:29: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   49 |                 if(year%4==0&&year%100!=0||year%400==0)
      |                    ~~~~~~~~~^~~~~~~~~~~~~
foo.cc:50:28: warning: 'sum' may be used uninitialized [-Wmaybe-uninitialized]
   50 |                         sum=sum+1;
      |                         ~~~^~~~~~
foo.cc:5:24: note: 'sum' was declared here
    5 |     int year,month,day,sum;
      |                        ^~~

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