#include<bits/stdc++.h>
using namespace std;
const int maxn=5e6+10;
int n,m,a[maxn];
struct fan
{
	int l,r,sz;
	long long sum,lazy,lazy1;
}t[maxn];
void pushup(int rt)
{
	t[rt].sum=max(t[rt<<1].sum,t[rt<<1|1].sum);
}
void pushdown(int rt)
{
	if(t[rt].lazy1!=-1000000001)
	{
		t[rt<<1].lazy=t[rt<<1|1].lazy=0;
		t[rt<<1].sum=t[rt<<1|1].sum=t[rt].lazy1;
		t[rt<<1].lazy1=t[rt<<1|1].lazy1=t[rt].lazy1;
		t[rt].lazy1=-1000000001;
	}
}
void pushdown1(int rt)
{
	if(t[rt].lazy)
	{
		pushdown(rt);
		t[rt<<1].sum+=t[rt].lazy;
		t[rt<<1|1].sum+=t[rt].lazy;
		t[rt<<1].lazy+=t[rt].lazy;
		t[rt<<1|1].lazy+=t[rt].lazy;
		t[rt].lazy=0;
	}
}
void build(int x,int y,int rt)
{
	t[rt]={x,y,y-x+1,0,0,-1000000001};
	if(x==y)
	{
		t[rt].sum=a[x];
		return;
	}
	int mid=(x+y)>>1;
	build(x,mid,rt<<1);
	build(mid+1,y,rt<<1|1);
	pushup(rt);
}
void modify(int x,int y,long long k,int rt)
{
	if(t[rt].l>=x&&t[rt].r<=y)
	{
		t[rt].sum=k;
		t[rt].lazy1=k;
		return;
	}
	pushdown(rt);
	int mid=(t[rt].l+t[rt].r)>>1;
	if(x<=mid) modify(x,y,k,rt<<1);
	if(y>mid) modify(x,y,k,rt<<1|1);
	pushup(rt);
}
void modify1(int x,int y,long long k,int rt)
{
	if(t[rt].l>=x&&t[rt].r<=y)
	{
		t[rt].sum+=k;
		t[rt].lazy+=k;
		return;
	}
	pushdown1(rt);
	int mid=(t[rt].l+t[rt].r)>>1;
	if(x<=mid) modify1(x,y,k,rt<<1);
	if(y>mid) modify1(x,y,k,rt<<1|1);
	pushup(rt);
}
long long query(int x,int y,int rt)
{
	if(t[rt].l>=x&&t[rt].r<=y) return t[rt].sum;
	pushdown1(rt);
	int mid=(t[rt].l+t[rt].r)>>1;
	long long ans=-INT_MAX;
	if(x<=mid) ans=(ans,query(x,y,rt<<1));
	if(y>mid) ans=max(ans,query(x,y,rt<<1|1));
	return ans;
}
int main()
{
	cin>>n>>m;
	for(int i=1;i<=n;i++) cin>>a[i];
	build(1,n,1);
	for(int i=1;i<=m;i++)
	{
		int op,x,y,k;
		cin>>op>>x>>y;
		if(op==1)
		{
			cin>>k;
			modify(x,y,k,1);
		}
		if(op==2)
		{
			cin>>k;
			modify1(x,y,k,1);
		}
		if(op==3)
		{
			cout<<query(x,y,1)<<endl;
		}
	}
	return 0;
}