foo.cc: In function 'int IsLeapYear(int)':
foo.cc:7:15: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if (year%4==0&&year%100!=0||year%400==0)
      ~~~~~~~~~^~~~~~~~~~~~~
foo.cc: At global scope:
foo.cc:49:40: error: ISO C++ forbids declaration of 'WeekdayOfTheFirstDay' with no type [-fpermissive]
 WeekdayOfTheFirstDay(int year,int month)
                                        ^

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