var
i,j,k,n,m,s,x,max,maxx:longint;
p,pp:boolean;
a,b,c,v:Array[0..500] of integer;
f:Array[0..500] of boolean;
ans:array[0..500] of integer;
money:Array[0..500] of longint;
function l(q,w:integer):longint;
begin
  l:=abs(q-w);
end;
begin
  fillchar(f,sizeof(f),true);
  readln(n);
  if n=0 then
  begin
    writeln(0);
    halt;
  end;
  if n=1 then
  begin
    writeln(1);
    writeln(1);
    halt;
  end;
  max:=-1;
  for i:=1 to n do
  v[i]:=i;
  for i:=1 to n do
  begin
    readln(a[i],b[i]);
    if a[i]>b[i] then
    begin
      m:=a[i];
      a[i]:=b[i];
      b[i]:=m;
    end;
  end;
  for i:=1 to n-1 do
    for j:=1 to n-i do
    if l(a[j],b[j])>l(a[j+1],b[j+1]) then
    begin
      x:=a[j];
      a[j]:=a[j+1];
      a[j+1]:=x;
      x:=b[j];
      b[j]:=b[j+1];
      b[j+1]:=x;
      x:=v[j];
      v[j]:=v[j+1];
      v[j+1]:=x;
    end;
    for i:=2 to n do
    begin
      if (a[i]=a[i-1]) and (b[i]=b[i-1]) then f[i]:=false;
    end;
  fillchar(money,sizeof(money),255);
  fillchar(c,sizeof(c),0);
  money[1]:=1;
  for i:=2 to n do
  if f[i] then
  begin
    p:=true;
    m:=-1;
    for j:=i-1 downto 1 do
    if f[j] then
    begin
{      if ((a[j]=a[i]) and (b[j]<b[i])) or ((a[j]>a[i]) and (b[j]=b
[i])) or ((a[j]=a[i]) and (b[j]=b[i])) then
      begin
        p:=false;
        break;
      end;}
      if (a[j]>a[i]) and (b[j]<b[i]) and (money[j]=-1) then
      begin
        p:=false;
        break;
      end;
    end;
    if p then
    begin
      for j:=i-1 downto 1 do
      if f[j] then
      begin
        if (a[j]>a[i]) and (b[j]<b[i]) then
        begin
          m:=j;
          for k:=j-1 downto 1 do
          if f[k] then
          begin
          if ((a[k]>a[i]) and (b[k]<b[i])) and ((a[k]<=a[j]) or (b[k]
>=b[j])) then
            begin
              p:=false;
              break;
            end;
          end;
          break;
        end;
      end;
    end;
    if p then
    begin
      if m=-1 then money[i]:=1;
      if m<>-1 then
      begin
        money[i]:=money[m]+1;
        c[i]:=m;
      end;
      if max<money[i] then
      begin
        max:=money[i];
        maxx:=i;
      end;
    end;
  end;
  writeln(max);
  s:=1;
  k:=maxx;
  ans[1]:=v[maxx];
  while c[k]<>0 do
  begin
    s:=s+1;
    k:=c[k];
    ans[s]:=v[k];
  end;
  for i:=s downto 1 do
  write(ans[i],' ');
  writeln;
end.