60pts

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ldb long double
template<typename T>
inline void read(T &x){
	bool f=1; x=0; char ch=getchar();
	while(ch<'0'||ch>'9') {if(ch=='-') f=!f; ch=getchar();}
	while(ch>='0'&&ch<='9') {x=(x<<3)+(x<<1)+(ch-'0'); ch=getchar();}
	x=(f?x:-x); return ;
}
template<typename T>
inline void print(T x){
	if(x<0) {putchar('-'); x=-x;}
	if(x>9) print(x/10);
	putchar(x%10+'0'); return ;
}

const int inf=2e9;
int n,q,a[1000010],lazy1[4000010];
ll maxx[4000010],lazy2[4000010];
int kid,l,r,val;
void build(int k,int l,int r){
	lazy1[k]=inf;
	if(l==r) {maxx[k]=a[l]; return ;}
	int mid=(l+r)>>1;
	build(k<<1,l,mid); build((k<<1)|1,mid+1,r);
	maxx[k]=max(maxx[k<<1],maxx[(k<<1)|1]); return ;
}
//有maxx就直接去掉 
void pushdown(int k){
	if(lazy1[k]<inf)
	{
		lazy1[k<<1]=lazy1[(k<<1)|1]=lazy1[k];
		maxx[k<<1]=maxx[(k<<1)|1]=lazy1[k];
		lazy1[k]=inf;
	}
	lazy2[k<<1]+=lazy2[k]; lazy2[(k<<1)|1]+=lazy2[k];
	maxx[k<<1]+=lazy2[k]; maxx[(k<<1)|1]+=lazy2[k];
	lazy2[k]=0; return ;
}
void update1(int k,int l,int r,int lhs,int rhs,int pts){
	if(l>=lhs&&r<=rhs) {maxx[k]=lazy1[k]=pts; lazy2[k]=0; return ;}
	pushdown(k);
	int mid=(l+r)>>1;
	if(mid>=lhs) update1(k<<1,l,mid,lhs,rhs,pts);
	if(mid<rhs) update1((k<<1)|1,mid+1,r,lhs,rhs,pts);
	maxx[k]=max(maxx[k<<1],maxx[(k<<1)|1]); return ;
}
void update2(int k,int l,int r,int lhs,int rhs,int pts){
	if(l>=lhs&&r<=rhs){
		maxx[k]+=pts;
		if(lazy1[k]<inf) lazy1[k]+=pts;
		else lazy2[k]+=pts; return ;
	}
	pushdown(k);
	int mid=(l+r)>>1;
	if(mid>=lhs) update2(k<<1,l,mid,lhs,rhs,pts);
	if(mid<rhs) update2((k<<1)|1,mid+1,r,lhs,rhs,pts);
	maxx[k]=max(maxx[k<<1],maxx[(k<<1)|1]); return ;
}
ll query(int k,int l,int r,int lhs,int rhs){
	if(l>=lhs&&r<=rhs) return maxx[k];
	pushdown(k);
	int mid=(l+r)>>1; ll ans=-2e18;
	if(mid>=lhs) ans=max(ans,query(k<<1,l,mid,lhs,rhs));
	if(mid<rhs) ans=max(ans,query((k<<1)|1,mid+1,r,lhs,rhs));
	return ans;
}

int main(){
	read(n); read(q);
	for(int i=1;i<=n;i++) read(a[i]);
	build(1,1,n);
	for(int i=1;i<=q;i++){
		read(kid);
		if(kid==1) {read(l); read(r); read(val); update1(1,1,n,l,r,val);}
		else if(kid==2) {read(l); read(r); read(val); update2(1,1,n,l,r,val);}
		else {read(l); read(r); printf("%lld\n",query(1,1,n,l,r));}
	}
	return 0;
}