/in/foo.cc: In function 'int main()':
/in/foo.cc:32:8: error: storage size of 'a' isn't known
  int a[], int b[]; cin>>a[]>>b[];
        ^
/in/foo.cc:32:11: error: expected unqualified-id before 'int'
  int a[], int b[]; cin>>a[]>>b[];
           ^~~
/in/foo.cc:32:27: error: expected primary-expression before ']' token
  int a[], int b[]; cin>>a[]>>b[];
                           ^
/in/foo.cc:32:30: error: 'b' was not declared in this scope
  int a[], int b[]; cin>>a[]>>b[];
                              ^
/in/foo.cc:32:32: error: expected primary-expression before ']' token
  int a[], int b[]; cin>>a[]>>b[];
                                ^