#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 1e6 + 1, INF = -1e9;
int n, q, a[N], oper, l, r, x;
struct Tree
{
	int lbian = INF, ladd = 0;
	int maxx;
} tree[4 * N];
void pushup(int p)
{
	tree[p].maxx = max(tree[p * 2].maxx, tree[p * 2 + 1].maxx);
}
void build(int p, int l, int r)
{
	if (l == r)
	{
		tree[p].maxx = a[l];
		return;
	}
	int mid = l + r >> 1;
	build(p * 2, l, mid), build(p * 2 + 1, mid + 1, r);
	pushup(p);
}
void pushdown(int p)
{
	if (tree[p].lbian != INF)
	{
		tree[p * 2].lbian = tree[p * 2 + 1].lbian = tree[p].lbian;
		int mid = l + r >> 1;
		tree[p * 2].maxx = tree[p].lbian, tree[p * 2 + 1].maxx = tree[p].lbian, tree[p].lbian = INF;
	}
	if (tree[p].ladd != 0)
	{
		tree[p * 2].ladd += tree[p * 2 + 1].ladd = tree[p].ladd;
		int mid = l + r >> 1;
		tree[p * 2].maxx += tree[p].ladd, tree[p * 2 + 1].maxx += tree[p].ladd, tree[p].ladd = 0;
	}
}
void qbian(int p, int ql, int qr, int k, int l, int r)
{
	if (r < ql || l > qr) return;
	if (l >= ql && r <= qr)
	{
		tree[p].maxx = k, tree[p].lbian = k;
		return;
	}
	int mid = l + r >> 1;
	pushdown(p);
	qbian(p * 2, ql, qr, k, l, mid);
	qbian(p * 2 + 1, ql, qr, k, mid + 1, r);
	pushup(p);
}
void qjia(int p, int ql, int qr, long long k, int l, int r)
{
	if (r < ql || l > qr) return;
	if (ql <= l && qr >= r)
	{
		tree[p].ladd += k, tree[p].maxx += k;
		return;
	}
	pushdown(p);
	int mid = l + r >> 1;
	qjia(p * 2, ql, qr, k, l, mid), qjia(p * 2 + 1, ql, qr, k, mid + 1, r);
	pushup(p);
}
int askm(int p, int ql, int qr, int l, int r)
{
	if (l > qr || r < ql) return INF;
	if (l >= ql && r <= qr) return tree[p].maxx;
	int mid = l + r >> 1;
    pushdown(p);
	return max(askm(p * 2, ql, qr, l, mid), askm(p * 2 + 1, ql, qr, mid + 1, r));
}
signed main()
{
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	cin>>n>>q;
	for (int i = 1;i <= n;i++) cin>>a[i];
	build(1, 1, n);
	while (q--)
	{
		cin>>oper>>l>>r;
		if (oper == 1)
		{
			cin>>x;
			qbian(1, l, r, x, 1, n);
		}
		else if (oper == 2)
		{
			cin>>x;
			qjia(1, l, r, x, 1, n);
		}
		else cout<<askm(1, l, r, 1, n)<<'\n';
	}
}