/in/foo.cc: In function 'int ackermann(int, int)':
/in/foo.cc:15:49: error: expected ')' before 'n'
   15 |                 return ackermann(m-1,ackermann(m n-1));
      |                                               ~ ^~
      |                                                 )
/in/foo.cc:15:47: error: too few arguments to function 'int ackermann(int, int)'
   15 |                 return ackermann(m-1,ackermann(m n-1));
      |                                      ~~~~~~~~~^~~~
/in/foo.cc:3:5: note: declared here
    3 | int ackermann(int m,int n)
      |     ^~~~~~~~~