#include<iostream>
#include<cstring>
using namespace std;
#define ll long long
//push_up,b_t,push_down,addtag,query,update;
const ll N = 1e6;
const ll INF = 1e10;
ll a[N],tree[N<<2],tag_add[N<<2],tag_mo[N<<2];
int n,q,op;

inline ll lson(ll p){	return p<<1;	}
inline ll rson(ll p){	return p<<1|1;	}
inline void push_up(ll p){	tree[p] = max(tree[lson(p)],tree[rson(p)]);	}
inline void b_t(ll p,ll l,ll r){
	if(l == r){	tree[p] = a[l]; tag_mo[p] = INF; return;	}
	tag_mo[p] = INF;
	ll mid=(l+r)>>1;
	b_t(lson(p),l,mid);
	b_t(rson(p),mid+1,r);
	push_up(p);
}
inline void addtag(ll p,ll x,int t){
	if (t == 1){//改 
		tag_add[p] = 0;
		tag_mo[p] = x;
		tree[p] = x;
	}
	else{//加 
		if(tag_mo[p] == INF)	tag_add[p]+=x;
		else tag_mo[p]+=x;
		tree[p]+=x; 
	}
}
inline void push_down(ll p,ll l,ll r){
	if (tag_mo[p] == INF){
		addtag(lson(p),tag_add[p],2);
		addtag(rson(p),tag_add[p],2);
		tag_add[p] = 0;
	}
	else {
		addtag(lson(p),tag_mo[p],1);
		addtag(rson(p),tag_mo[p],1);
		tag_mo[p] = INF;
	}	
} 
ll query(ll nl,ll nr,ll p,ll l,ll r){
	if(nl<=l && nr>=r)	return tree[p];
	ll mid = (l+r)>>1;
	ll ans = -INF;
	push_down(p,l,r);
	if(nl<=mid)	ans = max(ans,query(nl,nr,lson(p),l,mid));
	if(nr>mid)	ans = max(ans,query(nl,nr,rson(p),mid+1,r)); 
	return ans;
}

inline void update(ll nl,ll nr,ll p,ll l,ll r,ll x,int t){
	if(nl<=l && nr>=r){
			if (t == 1){
				addtag(p,x,1);
				return; 
			}
			else {
				addtag(p,x,2);
				return;
			}
	}
	push_down(p,l,r);
	ll mid=(l+r)>>1;
	if(t == 1){
		if(nl<=mid)	update(nl,nr,lson(p),l,mid,x,1);
		if(nr>mid)	update(nl,nr,rson(p),mid+1,r,x,1);
	} 
	else {
		if(nl<=mid)	update(nl,nr,lson(p),l,mid,x,2);
		if(nr>mid)	update(nl,nr,rson(p),mid+1,r,x,2);
	}
	push_up(p);
}

int main(){
	cin>>n>>q;
	for (int i=1;i<=n;i++)	cin>>a[i];
	while(q--){
		cin>>op;
		if(op == 1){
			ll nl,nr,d;
			cin>>nl>>nr>>d;
			update(nl,nr,1,1,n,d,1);
		}
		if(op == 2){
			ll nl,nr,d;
			cin>>nl>>nr>>d;
			update(nl,nr,1,1,n,d,2);
		}
		if(op == 3){
			ll nl,nr;
			cin>>nl>>nr;
			cout<<query(nl,nr,1,1,n)<<"\n";
		}
//		cout<<tree[2]<<" "<<tree[3]<<endl;
	}
	return 0;
}