RT

#include <iostream>

using namespace std;
using ll = long long;

const ll kMaxN = 1e6 + 1;

ll n, m, a[kMaxN], t[kMaxN << 3], mo[kMaxN << 3], add[kMaxN << 3];

void build(ll x, ll l, ll r) {
	if (l > r) {
		t[x] = -1e9;
		return;
	}
	if (l == r) {
		t[x] = mo[x] = a[l];
		return;
	}
	mo[x] = -1e18;
	ll mid = (l + r) >> 1;
	build(x << 1, l, mid), build(x << 1 | 1, mid + 1, r);
	t[x] = max(t[x << 1], t[x << 1 | 1]);
}

void pushdown(ll x, ll l, ll r) {
	if (mo[x] != -1e18) {
		t[x << 1] = mo[x];
		t[x << 1 | 1] = mo[x];
		mo[x << 1] = mo[x << 1 | 1] = mo[x];
		add[x << 1] = add[x << 1 | 1] = 0;
		mo[x] = -1e18;
		add[x] = 0;
	} else if (add[x]) {
		t[x << 1] += add[x];
		t[x << 1 | 1] += add[x];
		(mo[x << 1]) && (mo[x << 1] += add[x]);
		(mo[x << 1 | 1]) && (mo[x << 1 | 1] += add[x]);
		add[x << 1] += add[x];
		add[x << 1 | 1] += add[x];
		add[x] = 0;
	}
}

void Add(ll x, ll l, ll r, ll a, ll b, ll d) {
	if (l > r || l > b || r < a) {
		return;
	}
	if (a <= l && r <= b) {
		if (mo[x] != -1e18) {
			mo[x] += d;
		} else {
			add[x] += d;
		}
		t[x] += d;
		return;
	}
	pushdown(x, l, r);
	ll mid = (l + r) >> 1;
	Add(x << 1, l, mid, a, b, d);
	Add(x << 1 | 1, mid + 1, r, a, b, d);
	t[x] = max(t[x << 1], t[x << 1 | 1]);
}

void Modify(ll x, ll l, ll r, ll a, ll b, ll d) {
	if (l > r || l > b || r < a) {
		return;
	}
	if (a <= l && r <= b) {
		t[x] = d;
		add[x] = 0;
		mo[x] = d;
		return;
	}
	pushdown(x, l, r);
	ll mid = (l + r) >> 1;
	Modify(x << 1, l, mid, a, b, d);
	Modify(x << 1 | 1, mid + 1, r, a, b, d);
	t[x] = max(t[x << 1], t[x << 1 | 1]);
}

ll query(ll x, ll l, ll r, ll a, ll b) {
	if (l > r || l > b || r < a) {
		return -1e18;
	}
	if (l >= a && r <= b) {
		return t[x];
	}
	pushdown(x, l, r);
	ll mid = (l + r) >> 1;
	return max(query(x << 1, l, mid, a, b), query(x << 1 | 1, mid + 1, r, a, b));
}

int main() {
	cin >> n >> m;
	for (ll i = 1; i <= n; i++) {
		cin >> a[i];
	}
	build(1, 1, n);
	for (ll op, l, r, x; m; m--) {
		cin >> op >> l >> r;
		if (op == 3) {
			cout << query(1, 1, n, l, r) << '\n';
		} else {
			cin >> x;
			if (op == 1) {
				Modify(1, 1, n, l, r, x);
			} else {
				Add(1, 1, n, l, r, x);
			}
		}
	}
	return 0;
}