#include <bits/stdc++.h>
#define int long long
using namespace std;
const int maxn = 1e6 + 5;
const int INF = LLONG_MAX;
struct node {
	int l, r, mx, lz1, lz2;
} t[maxn << 2];
int n, m, a[maxn];
void push_down(int i) {
	if (t[i].lz1 != INF) {
		t[i * 2].mx = t[i].lz1;
		t[i * 2 + 1].mx = t[i].lz1;
		t[i * 2].lz1 = t[i].lz1;
		t[i * 2 + 1].lz1 = t[i].lz1;
		t[i].lz1 = INF;
	}
	if (t[i].lz2) {
		t[i * 2].mx += t[i].lz2;
		t[i * 2 + 1].mx += t[i].lz2;
		t[i * 2].lz2 += t[i].lz2;
		t[i * 2 + 1].lz2 += t[i].lz2;
		t[i].lz2 = 0;
	}
}
void build(int i, int l, int r) {
	t[i].l = l, t[i].r = r, t[i].lz1 = INF;
	if (l == r) {
		t[i].mx = a[l];
		return;
	}
	int mid = l + r >> 1;
	build(i * 2, l, mid);
	build(i * 2 + 1, mid + 1, r);
	t[i].mx = max(t[i * 2].mx, t[i * 2 + 1].mx);
}
void upd1(int i, int l, int r, int d) {
	if (t[i].l >= l && t[i].r <= r) {
		t[i].lz1 = d;
		t[i].mx = d;
		return;
	}
	push_down(i);
	if (t[i * 2].r >= l) upd1(i * 2, l, r, d);
	if (t[i * 2 + 1].l <= r) upd1(i * 2 + 1, l, r, d);
	t[i].mx = max(t[i * 2].mx, t[i * 2 + 1].mx);
}
void upd2(int i, int l, int r, int d) {
	if (l <= t[i].l && t[i].r <= r) {
		t[i].mx += d;
		t[i].lz2 += d;
		return;
	}
	push_down(i);
	if (t[i * 2].r >= l) upd2(i * 2, l, r, d);
	if (t[i * 2 + 1].l <= r) upd2(i * 2 + 1, l, r, d);
	t[i].mx = max(t[i * 2].mx, t[i * 2 + 1].mx);
}
int query(int i, int l, int r) {
	if (l <= t[i].l && t[i].r <= r) {
		return t[i].mx;
	}
	push_down(i);
	int ans = -1;
	if (t[i * 2].r >= l) ans = max(ans, query(i * 2, l, r));
	if (t[i * 2 + 1].l <= r) ans = max(ans, query(i * 2 + 1, l, r));
	return ans;
}
signed main() {
	//freopen("1.in", "r", stdin);
	scanf("%lld %lld", &n, &m);
	for (int i = 1; i <= n; i++) {
		scanf("%lld", &a[i]);
	}
	build(1, 1, n);
	for (int i = 1; i <= m; i++) {
		int opt, x, y, d;
		scanf("%lld", &opt);
		if (opt == 1) {
			scanf("%lld %lld %lld", &x, &y, &d);
			upd1(1, x, y, d);
		}
		if (opt == 2) {
			scanf("%lld %lld %lld", &x, &y, &d);
			upd2(1, x, y, d);
		}
		if (opt == 3) {
			scanf("%lld %lld", &x, &y);
			printf("%lld\n", query(1, x, y));
		}
	}
}