public static void Solve()
{
var(N, Q) = Scanner.Scan <int, int>();
var A = Scanner.ScanEnumerable <int>().ToArray();
var seg = new SegTree <int>(A, (a, b) => Math.Max(a, b), -1);
for (var i = 0; i < Q; i++)
{
var(T, X, V) = Scanner.Scan <int, int, int>();
X--;
if (T == 1)
{
seg.Set(X, V);
}
else if (T == 2)
{
Console.WriteLine(seg.Prod(X, V));
}
else if (T == 3)
{
Console.WriteLine(seg.MaxRight(X, v => v < V) + 1);
}
}
}