> 同RE...
我也re啊，郁闷！
var
  i,j,k,si,l,r,l2,r2,n,q,ce,cei:longint;
  er:array[0..30]of longint;
  a,b,s,jl,jr:array[0..200000] of longint;
  f:array[0..200000,0..30]  of longint;
function max(a,b:longint):longint;
begin
  if a>b then exit(a) else exit(b);
end;
procedure rmq;
var
  i,j,k:longint;
begin
  for i:=1 to n do f[i,0]:=s[i];
  for j:=1 to trunc(ln(n)/ln(2))+1 do
  for i:=1 to n do
  begin
    if i+er[j]-1>n then continue;
    f[i,j]:=max(f[i,j-1],f[i+er[j-1],j-1])
  end;
end;
function qujian(i,j:longint):longint;
var
  k:longint;
begin
  if i>j then exit(0);
  k:=i-j+1;
  if k<>0 then k:=trunc(ln(k)/ln(2));
  exit(max(f[i,k],f[j-er[k]+1,k]));
end;
begin
while true do
begin
  read(n); if n=0 then exit;  readln(q);
  er[0]:=1;
  for i:=1 to 30 do
  er[i]:=er[i-1]*2  ;
  for i:=1 to n do
  begin
    read(a[i]);
  end;
  i:=1;
  si:=0;
  while true do
  begin
    k:=1;
    for j:=i+1 to n do
    begin
      if a[j]<>a[j-1] then break
      else inc(k);
    end;

    inc(si);
    s[si]:=k;

    for j:=i to i+k-1 do
    begin
      b[j]:=si;
      jl[j]:=j-i;
      jr[j]:=i+k-1-j;
    end;

    i:=i+k;
    if i>n then break;
  end;
  rmq;
  for i:=1 to q do
  begin
    readln(l,r)    ;
    if b[l]=b[r] then
    begin
      writeln(r-l+1);
      continue;
    end;
    l2:=l+jr[l]+1;
    r2:=r-jl[r]-1;
    writeln(max(max(qujian(b[l2],b[r2]),jr[l]+1),jl[r]+1))
  end;
end;
end.