#include <bits/stdc++.h>
#define ll long long
using namespace std;

const long long inf = -1e13;
const int N = 4e6 + 10;
int n, q, a[N];
struct tree {
	int l, r;
	ll d, lz1, lz2;//lz1传修改值， lz2传加数
} t[N];

ll read() {
	char c = getchar(); ll s = 0; short f = 1;
	while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}
	while(c >= '0' && c <= '9') {s = (s * 10) + c - '0'; c = getchar();}
	return s * f;
}

void pushup(int x) {
	t[x].d = max(t[x * 2].d, t[x * 2 + 1].d);
}

void build(int l, int r, int x) {
	t[x].l = l, t[x].r = r, t[x].lz1 = inf;
	if(l == r) {
		t[x].d = a[l];
		return;
	}
	int mid = (l + r) / 2;
	build(l, mid, x * 2);
	build(mid + 1, r, x * 2 + 1); 
	pushup(x);
}

void lazy_tag(int x) {
	if(t[x].lz1 != inf) {
		t[x * 2].lz1 = t[x * 2 + 1].lz1 = t[x].lz1;
		t[x * 2].d = t[x * 2 + 1].d = t[x].lz1;
		t[x * 2].lz2 = t[x * 2 + 1].lz2 = 0;
		t[x].lz1 = inf;
	}
	if(t[x].lz2) {
		t[x * 2].lz2 = t[x * 2 + 1].lz2 = t[x].lz2;
		t[x * 2].d += t[x].lz2;
		t[x * 2 + 1].d += t[x].lz2;
		t[x].lz2 = 0;
	}
}

void change(int l, int r, int p, ll v, int o) {
	if(l <= t[p].l && t[p].r <= r) {
		if(o == 1) {
			t[p].lz1 = v;
			t[p].d = v;
			t[p].lz2 = 0;
		}
		else {
			t[p].d += v;
			t[p].lz2 += v;
		}
		return;
	}
	lazy_tag(p);
	int mid = (t[p].l + t[p].r) >> 1;
	if(l <= mid) change(l, r, p * 2, v, o);
	if(r > mid) change(l, r, p * 2 + 1, v, o);
	pushup(p);
}

ll ask(int l, int r, int p) {
	if(l <= t[p].l && t[p].r <= r) {
		return t[p].d;
	}
	int mid = (t[p].l + t[p].r) >> 1;
	ll val = inf;
	lazy_tag(p);
	if(l <= mid) val = max(val, ask(l, r, p * 2));
	if(r > mid) val = max(val, ask(l, r, p * 2 + 1));
	return val;
}

int main() {
	cin >> n >> q;
	for(int i = 1; i <= n; i++) cin >> a[i];
	build(1, n, 1);
	while(q--) {
		int o = read(), l =read(), r = read();
		if(o == 1) {
			ll x = read();
			change(l, r, 1, x, 1);
		}//[l, r] += x
		if(o == 2) {
			ll x = read();
			change(l, r, 1, x, 2);
		}//[l, r] = x
		if(o == 3) {
			cout << ask(l, r, 1) << endl;
		}//max
	}
	return 0;
}

本蒟蒻只A了1和3，求助各位大佬