foo.cc: In function 'bool reng(int)':
foo.cc:4:25: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    4 |  return y%400==0||y%4==0&&y%100;
      |                   ~~~~~~^~~~~~~
foo.cc: In function 'int md(int, int)':
foo.cc:11:14: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   11 |  else if(m<=7&&m%2||m>=8&&m%2==0)return 31;
      |          ~~~~^~~~~

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