foo.cc: In function 'int main()':
foo.cc:46:30: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   46 |         if(n1%400==0||n1%4==0&&n1%100!=0)
      |                       ~~~~~~~^~~~~~~~~~~
foo.cc:49:29: warning: 'sum' may be used uninitialized [-Wmaybe-uninitialized]
   49 |                         sum = sum+1;
      |                         ~~~~^~~~~~~
foo.cc:5:22: note: 'sum' was declared here
    5 |         int n1,n2,n3,sum;
      |                      ^~~

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