foo.cc: In function 'int WeekdayOfTheFirstDay(int, int)':
foo.cc:58:16: warning: unused variable 'count' [-Wunused-variable]
  int a=0,i,j,c,count;
                ^~~~~
foo.cc: In function 'int main()':
foo.cc:74:8: warning: unused variable 'b' [-Wunused-variable]
  int a,b=0,c=0,i,d,year,month;
        ^
foo.cc: In function 'int DaysOfMonth(int, int)':
foo.cc:54:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

[Hydro](https://hydro.ac)提供评测服务