program LCA(Tarjan);

type arr=record

     u,v,w,next:longint;

     end;

const maxn=;

      maxm=;

var eg:array[..maxm*] of arr;

    last,lasq,ans,fa:array[..maxn] of longint;

    flag:array[..maxn] of boolean;

    n,i,j,q,x,y:longint;

procedure add(u,v:longint);

begin

  inc(j);

  eg[j].u:=u;

  eg[j].v:=v;

  eg[j].next:=last[u];

  last[u]:=j;

end;

procedure adt(u,v,w:longint);

begin

  inc(j);

  eg[j].u:=u;

  eg[j].v:=v;

  eg[j].w:=w;

  eg[j].next:=last[u];

  lasq[u]:=j;

end;

function find(x:longint):longint;

begin

  if fa[x]=x then exit(x);

  fa[x]:=find(fa[x]);

  exit(fa[x]);

end;

procedure lca(u:longint);

var v,i:longint;

begin

  i:=last[u];

  while i<>- do

    begin

      v:=eg[i].v;

      if not flag[v] then

        begin

          flag[v]:=true;

          lca(v); fa[v]:=u;

        end;

      i:=eg[i].next;

    end;

  i:=lasq[u];

  while i<>- do

    begin

      v:=eg[i].v;

      if flag[v] and (ans[eg[i].w]=-) then

        ans[eg[i].w]:=find(v);

      i:=eg[i].next;

    end;

end;

begin

  for i:= to maxn do begin last[i]:=-; lasq[i]:=-; end;

  j:=-;

  readln(n,q);

 for i:= to n- do

    begin

      readln(x,y);

      add(x,y);

      add(y,x);

    end;

  for i:= to q do

    begin

      readln(x,y);

      adt(x,y,i);

      adt(y,x,i);

      ans[i]:=-;

    end;

  fillchar(flag,sizeof(flag),false);

  for i:= to n do fa[i]:=i;

  flag[]:=true;

  lca();

  for i:= to q do writeln(ans[i]);

end.