foo.cc: In function ‘long long int turnl(long long int)’:
foo.cc:21:1: warning: control reaches end of non-void function [-Wreturn-type]
   21 | }
      | ^
foo.cc: In function ‘long long int turnr(long long int)’:
foo.cc:31:1: warning: control reaches end of non-void function [-Wreturn-type]
   31 | }
      | ^