#include<bits/stdc++.h>
#define inf LONG_LONG_MIN
#define ll long long
using namespace std;
const int N=1e5+7;
struct ST
{
	int l,r;
	ll maxn,covertag,addtag;
}tree[N<<2];
int a[N],n,q;
void pushup(int x)
{
	tree[x].maxn=max(tree[x<<1].maxn,tree[x<<1|1].maxn);
	return;
}
void build(int x,int l,int r)
{
	tree[x]={l,r,inf};
	if(l==r)
	{
		tree[x]={l,r,a[l],inf,0};
		return;
	} 
	int mid=l+r>>1;
	build(x<<1,l,mid);
	build(x<<1|1,mid+1,r);
	pushup(x);
	return;
}
void pushdown(int x)
{
	ST &rt=tree[x],&ls=tree[x<<1],&rs=tree[x<<1|1];
	if(rt.covertag!=inf)
	{
		ls.covertag=ls.maxn=rt.covertag;
		rs.covertag=rs.maxn=rt.covertag;
		ls.addtag=rs.addtag=0;
		rt.covertag=inf;
	}
	if(rt.addtag)
	{
		ls.addtag+=rt.addtag;
		rs.addtag+=rt.addtag;
		ls.maxn+=rt.addtag;
		rs.maxn+=rt.addtag;
		rt.addtag=0; 
	}
	return;
}
void cover(int x,int l,int r,int k)
{
	if(l<=tree[x].l&&r>=tree[x].r)
	{
		tree[x].addtag=0;
		tree[x].maxn=tree[x].covertag=k;
		return;
	}
	pushdown(x);
	int mid=tree[x].l+tree[x].r>>1;
	if(l<=mid)
		cover(x<<1,l,r,k);
	if(r>mid)
		cover(x<<1|1,l,r,k);
	pushup(x);
	return;
}
void add(int x,int l,int r,int k)
{
	if(l<=tree[x].l&&r>=tree[x].r)
	{
		tree[x].addtag+=k;
		tree[x].maxn+=k;
		return;
	}
	pushdown(x);
	int mid=tree[x].l+tree[x].r>>1;
	if(l<=mid)
		add(x<<1,l,r,k);
	if(r>mid)
		add(x<<1|1,l,r,k);
	pushup(x);
	return; 
}
ll query(int x,int l,int r)
{
	if(l<=tree[x].l&&r>=tree[x].r)
		return tree[x].maxn;
	pushdown(x);
	ll ans=inf;
	int mid=tree[x].l+tree[x].r>>1;
	if(l<=mid)	
		ans=max(ans,query(x<<1,l,r));
	if(r>mid)
		ans=max(ans,query(x<<1|1,l,r));
	return ans;	
}
void print()
{
	for(int i=1;i<=n;i++)
	{
		printf("%lld ",query(1,i,i));
	} 
	putchar('\n');
	return;
}
int main()
{
	scanf("%d%d",&n,&q);
	for(int i=1;i<=n;i++)
	{
		scanf("%d",&a[i]);
	}
	build(1,1,n);
//	print();
	while(q--)
	{
		int op,l,r,x;
		scanf("%d%d%d",&op,&l,&r);
		if(op==1)
		{
			scanf("%d",&x);
			cover(1,l,r,x);
//			print(); 
		}
		if(op==2)
		{
			scanf("%d",&x);
			add(1,l,r,x);
//			print();
		}
		if(op==3)
			printf("%lld\n",query(1,l,r))/*,print()*/;
	}
	return 0;
}