#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
const int N = 1e6 + 5, B = 1e4;
const ll INF = 1e18;
int n, m, len, cnt;
int id[N];
ll a[N],maxn[B],t1[B],t2[B];
void add (int l, int r, ll k)
{
	for (int i = l; i <= r; i ++)
	{
		if (i % len == 1)
		{
			maxn[id[i]] += k;
			t1[id[i]] += k;
			i += len - 1;
		}
		else
		{
			a[i] += k;
			maxn[id[i]] = max (maxn[id[i]], a[i]);
		}
	}
}
void update (int l, int r, ll x)
{
	for (int i = l; i <= n; i ++)
	{
		if (i % len == 1)
		{
			maxn[id[i]] = x;
			t2[id[i]] = x;
			t1[id[i]] = 0;
			i += len - 1;
		}
		else
		{
			a[i] = x;
			maxn[id[i]] = max (maxn[id[i]], a[i]);
		}
	}
}
ll query (int l, int r)
{
	ll ans=-INF;
	for (int i = l; i <= r; i ++)
	{
		if (i % len == 1)
		{
			ans = max (ans, maxn[id[i]]);
			i += len - 1;
		}
		else
		{
			ll temp = t2[id[i]];
			if (temp == -INF)
			{
				temp = a[i];
			}
			ans = max (ans, temp + t1[id[i]]);
		}
	}
	return ans;
}
int main ()
{
	scanf ("%d %d", &n, &m);
	len = sqrt (n);
	for (int i = 1; i <= n; i ++)
	{
		scanf ("%d", &a[i]);
		if (i % len == 1)
		{
			cnt ++;
		}
		id[i] = cnt;
		maxn[cnt] = max (maxn[cnt], a[i]);
		t2[cnt] = -INF;
	}
	while (m --)
	{
		int op, l, r;
		scanf ("%d %d %d", &op, &l, &r);
		if (op == 1)
		{
			ll x;
			scanf ("%lld", &x);
			add (l, r, x);
		}
		else if (op == 2)
		{
			ll x;
			scanf ("%lld", &x);
			update (l, r, x);
		}
		else
		{
			printf ("%lld \n", query (l, r));
		}
	}
	return 0;
}