#include <bits/stdc++.h>
using namespace std;
#define int long long
const int maxn=2e6+10;
int null=LONG_LONG_MAX;
struct node{
	int lazy1,lazy2;//赋值的优先级在加法前面
	int val,l,r;
}tr[maxn*4];
int a[maxn];

void pushup(int rt){
	tr[rt].val=max(tr[rt*2].val,tr[rt*2+1].val);
}

inline void coverdown(int rt)
{
	if(tr[rt].lazy1!=null)
	{
		tr[rt*2].lazy2=tr[rt*2+1].lazy2=0;
		tr[rt*2].val=tr[rt*2+1].val=tr[rt].lazy1;
		tr[rt*2].lazy1=tr[rt*2+1].lazy1=tr[rt*2].lazy1;
		tr[rt].lazy1=null;
	}
}

inline void sumdown(int rt)
{
	if(tr[rt].lazy2)
	{
		coverdown(rt);
		tr[rt*2].val+=tr[rt].lazy2,tr[rt*2+1].val+=tr[rt].lazy2;
		tr[rt*2].lazy2+=tr[rt].lazy2,tr[rt*2+1].lazy2+=tr[rt].lazy2;
		tr[rt].lazy2=0;
	}
}
inline void pushdown(int rt)
{
	coverdown(rt);
	sumdown(rt);
}
void build(int rt,int l,int r){
	tr[rt].l=l,tr[rt].r=r;
	if(l==r){
		tr[rt].val=a[l];
		tr[rt].lazy1=null;
		tr[rt].lazy2=0;
		return ;
	}
	int mid=(l+r)/2;
	build(rt*2,l,mid);
	build(rt*2+1,mid+1,r);
	pushup(rt);
}



void modify(int rt,int x,int y,int k){//区间赋值为k
	int l=tr[rt].l,r=tr[rt].r;
	if(x<=l&&r<=y){
		tr[rt].lazy2=0;
		tr[rt].lazy1=tr[rt].val=k;
		return ;
	}
	pushdown(rt);
	int mid=(l+r)/2;
	if(x<=mid) modify(rt*2,x,y,k);
	if(y>mid) modify(rt*2+1,x,y,k);
	pushup(rt);
}

void update(int rt,int x,int y,int k){
	int l=tr[rt].l,r=tr[rt].r;
	if(x<=l&&r<=y){
		pushdown(rt);
		//tr[rt].lazy2+=k;
		tr[rt].lazy2+=k;
		tr[rt].val+=k;
		return ;
	}
	pushdown(rt);
	int mid=(l+r)/2;
	if(x<=mid) update(rt*2,x,y,k);
	if(y>mid) update(rt*2+1,x,y,k);
	pushup(rt);
}

int query(int rt,int x,int y){
	int l=tr[rt].l,r=tr[rt].r;
	if(r<x||l>y) return LONG_LONG_MIN;
	if(x<=l&&r<=y){
		return tr[rt].val;
	}
	pushdown(rt);
	int mid=(l+r)/2,ans=LONG_LONG_MIN;
	if(x<=mid) ans=max(ans,query(rt*2,x,y));
	if(y>mid) ans=max(ans,query(rt*2+1,x,y));
	return ans;
}

signed main(){
	ios::sync_with_stdio(false);
	int n,q;
	cin >> n >> q;
	for(int i=1;i<=n;i++){
		cin >> a[i];
	}
	build(1,1,n);
	for(int i=1;i<=n*4;i++) tr[i].lazy1=null;
	while(q--){
		int op,x,y;
		cin >> op >> x >> y;
		if(op==1){
			int k;
			cin >> k;
			modify(1,x,y,k);
		}if(op==2){
			int k;
			cin >> k;
			update(1,x,y,k);
		}if(op==3){
			cout << query(1,x,y) << endl;
		}
	}
}