/in/foo.cc: In function 'int f(int)':
/in/foo.cc:6:7: error: 'retrue' was not declared in this scope
  else retrue f(i-1)*(4*n-2)/(n+1);
       ^~~~~~
/in/foo.cc:7:1: warning: control reaches end of non-void function [-Wreturn-type]
 } 
 ^