// Arhiva educationala - Arbori de intervale
var
	n, m, i2, i, t, a, b, poz, val : longint;
	v : array[1..400100] of longint;
	s : array[1..1000000] of char;
	f, g : text;

function query   (nod, st, dr : longint) : longint;
var
	m1, m2, mij, t : longint;
begin
if (poz <= st) and (dr <= val) then
	begin
	query := v[nod]; exit
	end;
mij := (st+dr) shr 1; m1 := 0; m2 := 0;
t := nod shl 1;
if (poz <= mij) then
	m1 := query (t, st, mij);
if (mij < val) then
	m2 := query (t + 1, mij+1, dr);
if (m1 >= m2) then query := m1 else query := m2;
end;

procedure update (nod, st, dr : longint);
var
    mij, t: longint;
begin
if (st = poz) and (dr = poz) then
	begin v[nod] := val; exit; end;
mij := (st + dr) shr 1;
t := nod shl 1;
if (poz <= mij) then
	update (t, st, mij)
else
	update (t + 1, mij+1, dr);
if (v[t] >= v[t+1]) then v[nod] := v[t] else v[nod] := v[t+1];
end;

begin
assign	(f, 'arbint.in');	assign 	(g, 'arbint.out');
reset	(f);				rewrite	(g);
readln	(f, n, m);

read    (f, s);

i:=1; poz:= 0;
while (s[i] <> #0) do
    begin
    a := 0; inc(poz);
    while (s[i] <> #0) and (s[i]<>#32) do
        begin
        a := a*10+ord(s[i])-48;
        inc(i);
        end;
    update	(1, 1, n);
    inc(i);
    end;

readln	(f);
for i := 1 to m do
	begin
	readln	(f, t, poz, val);
	if (t = 1) then
		update	(1, 1, n)
	else
		writeln	(g, query (1, 1, n));
	end;
close	(f);				close	(g);
end.