foo.cc: In function 'int main()':
foo.cc:21:20: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   21 |    case 2:if(y%4==0&&y%100!=0||y%400==0)d=29;
      |              ~~~~~~^~~~~~~~~~
foo.cc:25:13: warning: 'd' may be used uninitialized in this function [-Wmaybe-uninitialized]
   25 |  std::cout<<d;
      |             ^

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