#include<bits/stdc++.h>
using namespace std;
const int maxn=1000010;
struct node{
	int l,r,v,laz1,laz2,sum,mx;
}a[4*maxn];
int n,q,b[maxn];
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<<1)+(x<<3)+(ch-'0');
		ch=getchar();
	}
	return x*f;
}
void t_build(int l,int r,int v)
{
	a[v].l=l;
	a[v].r=r;
	a[v].laz1=0;
	a[v].laz2=0;
	if(l==r)
	{
		a[v].mx=b[l];
		return ;
	}
	int mid=(l+r)>>1;
	t_build(l,mid,v<<1);
	t_build(mid+1,r,(v<<1)|1);
	a[v].mx=max(a[v<<1].mx,a[(v<<1)|1].mx);
	return ; 
}
void update(int x,int y,int v,int k,bool flag)
{
	if(!flag)
	{
		if(a[v].l>=x&&a[v].r<=y)
		{
			a[v].laz1=k;
			a[v].laz2=0;
			a[v].mx=k;
			return ;
		}
		if(a[v].laz1)
		{
			a[v<<1].laz1=a[v].laz1;
			a[v<<1].laz2=0;
			a[(v<<1)|1].laz1=a[v].laz1;
			a[(v<<1)|1].laz2=0;
			a[v].laz1=0;
			a[v].laz2=0;
		}
		int mid=(a[v].r+a[v].l)>>1;
		if(y<=mid) update(x,y,v<<1,k,0);
		else if(x>mid) update(x,y,(v<<1)|1,k,0);
		else{
			update(x,mid,v<<1,k,0);
			update(mid+1,y,(v<<1)|1,k,0);
		}
	}//修改 
	
	else if(flag)
	{
		if(a[v].l>=x&&a[v].r<=y)
		{
			a[v].laz1=0;
			a[v].laz2+=k;
			a[v].mx=a[v].mx+k;
			return ;
		}
		if(a[v].laz2)
		{
			a[v<<1].laz2+=a[v].laz2;
			a[v<<1].laz1=0;
			a[(v<<1)|1].laz2+=a[v].laz2;
			a[(v<<1)|1].laz1=0;
			a[v].laz2=0;
			a[v].laz1=0;
		}
		int mid=(a[v].r+a[v].l)>>1;
		if(y<=mid) update(x,y,v<<1,k,1);
		else if(x>mid) update(x,y,(v<<1)|1,k,1);
		else{
			update(x,mid,v<<1,k,1);
			update(mid+1,y,(v<<1)|1,k,1);
		}
	}//加数 
	a[v].mx=max(a[v<<1].mx,a[(v<<1)|1].mx);
	return ;
}
int t_find(int x,int y,int v)
{
	if(a[v].l>=x&&a[v].r<=y)
	{
		if(a[v].laz1) return a[v].laz1;
		else if(a[v].laz2) return a[v].laz2+a[v].mx;
		else return a[v].mx;
	} 
	if(a[v].laz1)
	{
			a[v<<1].laz1=a[v].laz1;
			a[v<<1].laz2=0;
			a[(v<<1)|1].laz1=a[v].laz1;
			a[(v<<1)|1].laz2=0;
			a[v].laz1=0;
			a[v].laz2=0;
	}
	else if(a[v].laz2)
	{
		a[v<<1].laz2+=a[v].laz2;
		a[v<<1].laz1=0;
		a[(v<<1)|1].laz2+=a[v].laz2;
		a[(v<<1)|1].laz1=0;
		a[v].laz2=0;
		a[v].laz1=0;
		
	}
	int mid=(a[v].l+a[v].r)>>1;
	if(y<=mid) return t_find(x,y,v<<1);
		else if(x>mid) return t_find(x,y,(v<<1)|1);
		else{
			return max(t_find(x,mid,v<<1),t_find(mid+1,y,(v<<1)|1));
		}
	
}
int main()
{
	n=read();
	q=read();
	for(int i=1;i<=n;i++) b[i]=read();
	t_build(1,n,1);
	while(q--)
	{
		int op,x,y,k;
		op=read();
		if(op==1)
		{
			x=read(),y=read(),k=read();
			update(x,y,1,k,0);
		}
		else if(op==2)
		{
			x=read(),y=read(),k=read();
			update(x,y,1,k,1);
		}
		else {
			x=read(),y=read();
			cout<<t_find(x,y,1)<<endl;
		}
	}
    return 0;
}

只过了#1，玄关