foo.cc: In function 'int IsLeapYear(int)':
foo.cc:9:30: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if(year%400==0 || year%4==0 && year%100!=0)
                    ~~~~~~~~~~^~~~~~~~~~~~~~
foo.cc: In function 'int WeekdayOfTheFirstDay(int, int)':
foo.cc:59:6: warning: unused variable 'a' [-Wunused-variable]
  int a,b,c,i,j,y,n,z,sum=0;
      ^
foo.cc:59:10: warning: unused variable 'c' [-Wunused-variable]
  int a,b,c,i,j,y,n,z,sum=0;
          ^
foo.cc: In function 'int main()':
foo.cc:96:25: warning: unused variable 'b' [-Wunused-variable]
  int year,month,i,c,j,d,b;
                         ^
foo.cc: In function 'int DaysOfMonth(int, int)':
foo.cc:55:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

[Hydro](https://hydro.ac)提供评测服务