#include<iostream>
#include<climits>
using namespace std;
using ll=long long;
const int N=1e6+9;
ll a[N],t[N*4],lazy1[N*4];
bool lazy2[N*4]; 
int op,l,r,x,n,q;
inline int lc(int p){return p<<1;}
inline int rc(int p){return p<<1|1;}
void pushUp(int p){
	t[p]=max(t[lc(p)],t[rc(p)]);
}
void buildTree(int p,int l,int r){
	if(l==r){
		t[p]=a[l];
		return;
	}
	int mid=(l+r)>>1;
	buildTree(lc(p),l,mid);
	buildTree(rc(p),mid+1,r);
	pushUp(p);
}
void movetag(int p,ll c){
	t[p]+=c;
	lazy1[p]+=c;
}
void change(int p,ll c){
	lazy2[p]=1;
	lazy1[p]=0;
	t[p]=c;
}
void pushDown(int p){
	if(lazy2[p]){
		change(lc(p),t[p]);
		change(rc(p),t[p]);
		lazy2[p]=0;
	}
	else{
		movetag(lc(p),lazy1[p]);
		movetag(rc(p),lazy1[p]);
		lazy1[p]=0;
	}
}
void update(int p,int l,int r,int ql,int qr,ll c){
	if(ql<=l&&r<=qr){
		t[p]=c;
		lazy1[p]=0;
		lazy2[p]=1;
		return ;
	}
	pushDown(p);
	int mid=(l+r)>>1;
	if(ql<=mid){
		update(lc(p),l,mid,ql,qr,c);
	}
	if(mid<qr){
		update(rc(p),mid+1,r,ql,qr,c);
	}
	pushUp(p);
}
void add(int p,int l,int r,int ql,int qr,ll c){
	if(ql<=l&&r<=qr){
		if(lazy2[p]){
			pushDown(p);
		}
		t[p]+=c;
		lazy1[p]+=c;
		return ;
	}
	pushDown(p);
	int mid=(l+r)>>1;
	if(ql<=mid){
		add(lc(p),l,mid,ql,qr,c);
	}
	if(mid<qr){
		add(rc(p),mid+1,r,ql,qr,c);
	}
	pushUp(p);
}
ll query(int p,int l,int r,int ql,int qr){
	if(ql<=l&&r<=qr){
		return t[p];
	}
	pushDown(p);
	int mid=(l+r)>>1;
	ll ans=LLONG_MIN;
	if(ql<=mid){
		ans=max(ans,query(lc(p),l,mid,ql,qr));
	}
	if(mid<qr){
		ans=max(ans,query(rc(p),mid+1,r,ql,qr));
	}
	return ans;
}
int main(){
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	cin>>n>>q;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	buildTree(1,1,N);
	while(q--){
		cin>>op;
		switch(op){
			case 1:
				cin>>l>>r>>x;
				update(1,1,N,l,r,x);
				break;
			case 2:
				cin>>l>>r>>x;
				add(1,1,N,l,r,x);
				break;
			default:
				cin>>l>>r;
				cout<<query(1,1,N,l,r)<<endl;
		}
	}
	return 0;
}