#include<iostream>  
#include<cmath>  
#include<stdio.h>  
using namespace std;  
typedef long long ll;  
const int N = 1000010;  
ll arr[N], maxx[N*4], add[N*4], change[N*4];  
bool update[N*4];  
inline int read()  
{  
	int x = 0, f = 1; char ch = getchar();   
	while (ch < '0' || ch>'9'){if (ch == '-') f = -1; ch = getchar(); }  
	while (ch >= '0' && ch <= '9') { x = x * 10 + ch - 48; ch = getchar(); }  
	return x * f;  
}  
void up(int i）  
{  
	maxx[i] = max(maxx[i*2], maxx[i*2+1]);  
}  
void updatelazy(int i, ll v)    
{  
	maxx[i] = v;  
	add[i] = 0;  
	change[i] = v;  
	update[i] = true;  
}  
void addlazy(int i, ll v)  
{   
	maxx[i] += v;  
	add[i] += v;  
}   
void down(int i)  
{  
	if (update[i])  
	{  
		updatelazy(i*2, change[i]);  
		updatelazy(i*2+1, change[i]);  
		update[i] = false;  
	}  
	if (add[i] != 0)  
	{  
		addlazy(i*2, add[i]);  
		addlazy(i*2+1, add[i]);  
		add[i] = 0;  
	}  
}  
void build(int l, int r, int i)  
{  
	if (l == r)  
		maxx[i] = arr[l];  
	else  
	{  
		int mid = (l + r) / 2;  
		build(l, mid, i*2);  
		build(mid + 1, r, i*2+1);   
		up(i);  
	}  
	add[i] = 0;  
	change[i] = 0;  
	update[i] = false;  
}  
void Update(int jobl, int jobr, ll jobv, int l, int r, int i)  
{  
	if (jobl <= l && r <= jobr)  
		updatelazy(i, jobv);  
	else  
	{  
		int mid = (l + r) / 2;  
		down(i);  
		if (jobl <= mid)  
			Update(jobl, jobr, jobv, l, mid, i*2);  
		if (jobr > mid)  
			Update(jobl, jobr, jobv, mid + 1, r, i*2+1);  
		up(i);  
	}  
}  
void Add(int jobl, int jobr, ll jobv, int l, int r, int i)  
{  
	if (jobl <= l && r <= jobr)  
		addlazy(i, jobv);  
	else  
	{  
		int mid = (l + r) / 2;  
		down(i);  
		if (jobl <= mid)  
			Add(jobl, jobr, jobv, l, mid, i*2);  
		if (jobr > mid)  
			Add(jobl, jobr, jobv, mid + 1, r, i*2+1);  
		up(i);  
	}  
}  
ll query(int jobl, int jobr, int l, int r, int i)  
{  
	if (jobl <= l && r <= jobr)  
		return maxx[i];  
	int mid = (l + r) / 2;  
	down(i);  
	ll ans = -1000000010;  
	if (jobl <= mid)  
		ans = max(ans, query(jobl, jobr, l, mid, i*2));  
	if (jobr > mid)  
		ans = max(ans, query(jobl, jobr, mid + 1, r, i*2+1));  
	return ans;  
}  
int main()  
{  
    ll n, m;  
	n = read();  
	m = read();  
	for (ll i = 1; i <= n; i++)  
		arr[i] = read();  
	build(1, n, 1);  
	while (m--)  
	{  
		int zuo, x, y; ll k;  
		zuo = read();  
		if (zuo == 1)  
		{  
			x = read(); y = read(); k = read();  
			Update(x, y, k, 1, n, 1);  
		}  
		else if (zuo == 2)  
		{  
			x = read(); y = read(); k = read();  
			Add(x, y, k, 1, n, 1);  
		}  
		else  
		{  
			x = read(); y = read();  
			printf("%lld\n", query(x, y, 1, n, 1));  
		}  
	}  
}