foo.cc: In function 'int main()':
foo.cc:7:23: error: expected primary-expression before 'int'
  WeekdayOfTheFirstDay(int year,int month);
                       ^~~
foo.cc:7:32: error: expected primary-expression before 'int'
  WeekdayOfTheFirstDay(int year,int month);
                                ^~~
foo.cc:7:2: error: 'WeekdayOfTheFirstDay' was not declared in this scope
  WeekdayOfTheFirstDay(int year,int month);
  ^~~~~~~~~~~~~~~~~~~~

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