# Original solution
class SegmentTree():
    def __init__(self, arr, func=min, ie=2**63):
        self.h = (len(arr) - 1).bit_length()
        self.n = 2**self.h
        self.ie = ie
        self.func = func
        self.tree = [ie for _ in range(2 * self.n)]
        for i in range(len(arr)):
            self.tree[self.n + i] = arr[i]
        for i in range(1, self.n)[::-1]:
            self.tree[i] = func(self.tree[2 * i], self.tree[2 * i + 1])

    def set(self, idx, x):
        idx += self.n
        self.tree[idx] = x
        while idx:
            idx >>= 1
            self.tree[idx] = self.func(self.tree[2 * idx], self.tree[2 * idx + 1])

    def query(self, lt, rt):
        lt += self.n
        rt += self.n
        vl = vr = self.ie
        while rt - lt > 0:
            if lt & 1:
                vl = self.func(vl, self.tree[lt])
                lt += 1
            if rt & 1:
                rt -= 1
                vr = self.func(self.tree[rt], vr)
            lt >>= 1
            rt >>= 1
        return self.func(vl, vr)

import sys
input = sys.stdin.buffer.readline

N, Q = list(map(int, input().split()))
A = list(map(int, input().split()))

st = SegmentTree(A, max, 0)
res = list()

for _ in range(Q):
    t, x, y = list(map(int, input().split()))
    if t == 1:
        st.set(x - 1, y)
    elif t == 2:
        res.append(st.query(x - 1, y))
    else:
        hi = N + 1
        lo = x - 1
        while hi - lo > 1:
            mid = (hi + lo) // 2
            if st.query(x - 1, mid) >= y:
                hi = mid
            else:
                lo = mid
        res.append(lo + 1)

print(('\n'.join(map(str, res))))

# Optimized solution
class SegmentTree():
    def __init__(self, n, op, e):
        self.n = n
        self.op = op
        self.e = e
        self.log = (n - 1).bit_length()
        self.size = 1 << self.log
        self.d = [e] * (2 * self.size)

    def update(self, k):
        self.d[k] = self.op(self.d[2 * k], self.d[2 * k + 1])

    def build(self, arr):
        #assert len(arr) <= self.n
        for i in range(self.n):
            self.d[self.size + i] = arr[i]
        for i in range(1, self.size)[::-1]:
            self.update(i)

    def set(self, p, x):
        #assert 0 <= p < self.n
        p += self.size
        self.d[p] = x
        for i in range(1, self.log + 1):
            self.update(p >> i)

    def get(self, p):
        #assert 0 <= p < self.n
        return self.d[p + self.size]

    def prod(self, l, r):
        #assert 0 <= l <= r <= self.n
        sml = smr = self.e
        l += self.size
        r += self.size
        while l < r:
            if l & 1:
                sml = self.op(sml, self.d[l])
                l += 1
            if r & 1:
                r -= 1
                smr = self.op(self.d[r], smr)
            l >>= 1
            r >>= 1
        return self.op(sml, smr)

    def all_prod(self):
        return self.d[1]

    def max_right(self, l, f):
        #assert 0 <= l <= self.n
        #assert f(self.e)
        if l == self.n: return self.n
        l += self.size
        sm = self.e
        while True:
            while l % 2 == 0: l >>= 1
            if not f(self.op(sm, self.d[l])):
                while l < self.size:
                    l = 2 * l
                    if f(self.op(sm, self.d[l])):
                        sm = self.op(sm, self.d[l])
                        l += 1
                return l - self.size
            sm = self.op(sm, self.d[l])
            l += 1
            if (l & -l) == l: break
        return self.n

    def min_left(self, r, f):
        #assert 0 <= r <= self.n
        #assert f(self.e)
        if r == 0: return 0
        r += self.size
        sm = self.e
        while True:
            r -= 1
            while r > 1 and (r % 2): r >>= 1
            if not f(self.op(self.d[r], sm)):
                while r < self.size:
                    r = 2 * r + 1
                    if f(self.op(self.d[r], sm)):
                        sm = self.op(self.d[r], sm)
                        r -= 1
                return r + 1 - self.size
            sm = self.op(self.d[r], sm)
            if (r & -r) == r: break
        return 0

import sys
input = sys.stdin.buffer.readline

N, Q = list(map(int, input().split()))
A = tuple(map(int, input().split()))

st = SegmentTree(N, max, 0)
st.build(A)
res = []

for _ in range(Q):
    t, x, y = list(map(int, input().split()))
    if t == 1:
        st.set(x - 1, y)
    elif t == 2:
        res.append(st.prod(x - 1, y))
    else:
        res.append(st.max_right(x - 1, lambda z: z < y) + 1)

print(('\n'.join(map(str, res))))