const fi='baib.inp';
      fo='baib.out';

var a,b,c,ans:array[1..1000000] of longint;
    n,i,j,next:longint;
procedure init;
var i:longint;
begin
  assign(input,fi);reset(input);
  readln(n);
  for i:=1 to n do
    begin
      readln(a[i],b[i]);
      c[i]:=b[i];
    end;
  close(input);
end;

procedure qsort(l,r:longint);
var tm,i,j,p:longint;
begin
    if l>=r then exit;
    i:=l;
    j:=r;
    p:=c[(l+r) div 2];
    while i<=j do
      begin
        while c[i]<p do inc(i);
        while c[j]>p do dec(j);
        if i<=j then
           begin
             tm:=c[i];
             c[i]:=c[j];
             c[j]:=tm;
             inc(i);
             dec(j);
           end;
      end;
   qsort(i,r);qsort(l,j);
end;


function check(i:longint):boolean;
var l,r,m:longint;
begin
  l:=1;
  r:=n;
  while l<=r do
    begin
      m:=(l+r) div 2;
      if i<c[m] then r:=m-1;
      if i>c[m] then l:=m+1;
      if i=c[m] then exit(true);
    end;
 exit(false);
end;

procedure solve;
var i:longint;
begin
  for i:=1 to n do if not check(a[i]) then
    begin
      ans[1]:=a[i];
      break;
    end;
end;

procedure qsort2(l,r:longint);
var tm,i,j,p:longint;
begin
    if l>=r then exit;
    i:=l;
    j:=r;
    p:=a[(l+r) div 2];
    while i<=j do
      begin
        while a[i]<p do inc(i);
        while a[j]>p do dec(j);
        if i<=j then
           begin
             tm:=a[i];
             a[i]:=a[j];
             a[j]:=tm;
             tm:=b[i];
             b[i]:=b[j];
             b[j]:=tm;
             inc(i);
             dec(j);
           end;
      end;
   qsort2(i,r);qsort2(l,j);
end;

function nhiphan(i:longint):longint;
var l,r,m,cur:longint;
begin
  l:=1;
  r:=n;
  cur:=0;
  while l<= r do
    begin
      m:=(l+r) div 2;
      if a[m]>i then r:=m-1;
      if a[m]<i then l:=m+1;
      if a[m]=i then exit(b[m]);
    end;
end;
begin
  assign(output,fo);rewrite(output);
  init;
  qsort(1,n);
  solve;
  qsort2(1,n);
  ans[2]:=b[1];
  j:=3;
  i:=1;
  next:=b[1];
  while next<>0 do
    begin
      next:=nhiphan(ans[i]);
      ans[j]:=next;
      inc(i);
      inc(j);
    end;
  for i:=1 to j-2 do write(ans[i],' ');
  close(output);
end.