/in/foo.cc: In function 'int trans(int, int, int)':
/in/foo.cc:60:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'std::pair<int, int> next(int, int, int)':
/in/foo.cc:64:12: warning: 'ny' may be used uninitialized in this function [-Wmaybe-uninitialized]
  rg int nx,ny;
            ^~
/in/foo.cc:64:9: warning: 'nx' may be used uninitialized in this function [-Wmaybe-uninitialized]
  rg int nx,ny;
         ^~