/in/foo.cc: In function 'int main()':
/in/foo.cc:22:9: error: reference to 'rank' is ambiguous
  memset(rank,0,sizeof(rank));
         ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/type_traits:1482:12: note:                 template<class> struct std::rank
     struct rank
            ^~~~
/in/foo.cc:22:23: error: reference to 'rank' is ambiguous
  memset(rank,0,sizeof(rank));
                       ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/type_traits:1482:12: note:                 template<class> struct std::rank
     struct rank
            ^~~~
/in/foo.cc:38:7: error: reference to 'rank' is ambiguous
    if(rank[x]==0&&rank[y]==0) 
       ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/type_traits:1482:12: note:                 template<class> struct std::rank
     struct rank
            ^~~~
/in/foo.cc:38:19: error: reference to 'rank' is ambiguous
    if(rank[x]==0&&rank[y]==0) 
                   ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/type_traits:1482:12: note:                 template<class> struct std::rank
     struct rank
            ^~~~
/in/foo.cc:40:5: error: reference to 'rank' is ambiguous
     rank[x]=1;rank[y]=2;
     ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/type_traits:1482:12: note:                 template<class> struct std::rank
     struct rank
            ^~~~
/in/foo.cc:40:15: error: reference to 'rank' is ambiguous
     rank[x]=1;rank[y]=2;
               ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/type_traits:1482:12: note:                 template<class> struct std::rank
     struct rank
            ^~~~
/in/foo.cc:42:12: error: reference to 'rank' is ambiguous
    else if(rank[y]==0)
            ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/type_traits:1482:12: note:                 template<class> struct std::rank
     struct rank
            ^~~~
/in/foo.cc:44:8: error: reference to 'rank' is ambiguous
     if(rank[x]==1) rank[y]=2;
        ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/type_traits:1482:12: note:                 template<class> struct std::rank
     struct rank
            ^~~~
/in/foo.cc:44:20: error: reference to 'rank' is ambiguous
     if(rank[x]==1) rank[y]=2;
                    ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/type_traits:1482:12: note:                 template<class> struct std::rank
     struct rank
            ^~~~
/in/foo.cc:45:10: error: reference to 'rank' is ambiguous
     else rank[y]=1;
          ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/type_traits:1482:12: note:                 template<class> struct std::rank
     struct rank
            ^~~~
/in/foo.cc:49:8: error: reference to 'rank' is ambiguous
     if(rank[y]==1) rank[x]=2;
        ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/type_traits:1482:12: note:                 template<class> struct std::rank
     struct rank
            ^~~~
/in/foo.cc:49:20: error: reference to 'rank' is ambiguous
     if(rank[y]==1) rank[x]=2;
                    ^~~~
/in/foo.cc:10:9: note: candidates are: int rank [20002]
 int n,m,rank[MAX],fa[MAX];
         ^~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,