foo.cc: In function 'int main()':
foo.cc:13:17: warning: unused variable 'd' [-Wunused-variable]
  int year,month,d;
                 ^
foo.cc: In function 'int WeekdayOfTheFirsDay(int, int)':
foo.cc:42:6: warning: value computed is not used [-Wunused-value]
   sum+DaysOfYear(y);
   ~~~^~~~~~~~~~~~~~

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