foo.cc: In function 'void adiv(LL, LL)':
foo.cc:18:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define _for(i, a, b) for (register int i = (a); i < (b); ++i)
                                                    ^
foo.cc:50:5: note: in expansion of macro '_for'
     _for(i,0,tmp.size())
     ^~~~
foo.cc:18:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define _for(i, a, b) for (register int i = (a); i < (b); ++i)
                                                    ^
foo.cc:53:13: note: in expansion of macro '_for'
             _for(j,i,tmp.size())
             ^~~~
foo.cc:18:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define _for(i, a, b) for (register int i = (a); i < (b); ++i)
                                                    ^
foo.cc:59:5: note: in expansion of macro '_for'
     _for(j,1,tmp_pos.size())
     ^~~~
foo.cc:39:8: warning: unused variable 'back_x' [-Wunused-variable]
     LL back_x=x,back_y=y;
        ^~~~~~
foo.cc:39:17: warning: unused variable 'back_y' [-Wunused-variable]
     LL back_x=x,back_y=y;
                 ^~~~~~

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