foo.cc: In function ‘int main()’:
foo.cc:11:42: error: expected primary-expression before ‘<<’ token
   11 |                                 cout<<a<<<<b<<<<c<<;
      |                                          ^~
foo.cc:11:47: error: expected primary-expression before ‘<<’ token
   11 |                                 cout<<a<<<<b<<<<c<<;
      |                                               ^~
foo.cc:11:52: error: expected primary-expression before ‘;’ token
   11 |                                 cout<<a<<<<b<<<<c<<;
      |                                                    ^
foo.cc:13:42: error: expected primary-expression before ‘<<’ token
   13 |                                 cout<<a<<<<c<<<<b<<;
      |                                          ^~
foo.cc:13:47: error: expected primary-expression before ‘<<’ token
   13 |                                 cout<<a<<<<c<<<<b<<;
      |                                               ^~
foo.cc:13:52: error: expected primary-expression before ‘;’ token
   13 |                                 cout<<a<<<<c<<<<b<<;
      |                                                    ^
foo.cc:15:34: error: expected primary-expression before ‘<<’ token
   15 |                         cout<<c<<<<a<<<<b<<;
      |                                  ^~
foo.cc:15:39: error: expected primary-expression before ‘<<’ token
   15 |                         cout<<c<<<<a<<<<b<<;
      |                                       ^~
foo.cc:15:44: error: expected primary-expression before ‘;’ token
   15 |                         cout<<c<<<<a<<<<b<<;
      |                                            ^
foo.cc:19:39: error: expected primary-expression before ‘<<’ token
   19 |                                 cout<<<<b<<c<<<<a<<;
      |                                       ^~
foo.cc:19:47: error: expected primary-expression before ‘<<’ token
   19 |                                 cout<<<<b<<c<<<<a<<;
      |                                               ^~
foo.cc:19:52: error: expected primary-expression before ‘;’ token
   19 |                                 cout<<<<b<<c<<<<a<<;
      |                                                    ^
foo.cc:21:42: error: expected primary-expression before ‘<<’ token
   21 |                                 cout<<c<<<<b<<<<a<<;
      |                                          ^~
foo.cc:21:47: error: expected primary-expression before ‘<<’ token
   21 |                                 cout<<c<<<<b<<<<a<<;
      |                                               ^~
foo.cc:21:52: error: expected primary-expression before ‘;’ token
   21 |                                 cout<<c<<<<b<<<<a<<;
      |                                                    ^
foo.cc:23:34: error: expected primary-expression before ‘<<’ token
   23 |                         cout<<b<<<<a<<<<c<<;
      |                                  ^~
foo.cc:23:39: error: expected primary-expression before ‘<<’ token
   23 |                         cout<<b<<<<a<<<<c<<;
      |                                       ^~
foo.cc:23:44: error: expected primary-expression before ‘;’ token
   23 |                         cout<<b<<<<a<<<<c<<;
      |                                            ^