rt

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll
#define ls rt<<1
#define rs rt<<1|1
inline int rd(){
	int x=0,f=1;char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while('0'<=ch&&ch<='9')x=x*10+ch-'0',ch=getchar();
	return x*f;
}
const int N=1e6+7;
const int inf=1e18;
int n,q,a[N];
struct tree{
	int x,ldj,ldf;
}t[N<<2];

inline void pushup(int rt){
	t[rt].x=max(t[ls].x,t[rs].x);
}

inline void flazy(int rt,int l,int r,int F){
	t[rt].ldf=F;
	t[rt].ldj=0; 
	t[rt].x=F*(r-l+1);
	return; 
}

inline void addlazy(int rt,int l,int r,int C){
	t[rt].ldj+=C;
	t[rt].x+=C*(r-l+1);
	return; 
}

void pushdown(int rt,int l,int r){
    int mid=(l+r)>>1;
	if(t[rt].ldf!=inf){	
		flazy(ls,l,mid,t[rt].ldf);
		flazy(rs,mid+1,r,t[rt].ldf);
		t[rt].ldf=inf; 
	}
	if(t[rt].ldj){
		addlazy(ls,l,mid,t[rt].ldj);
		addlazy(rs,mid+1,r,t[rt].ldj);
		t[rt].ldj=0;
	}	
	return;
}

void gz(int rt,int l,int r){
	t[rt].ldf=inf;
	t[rt].ldj=0;
	if(l==r){
		t[rt].x=a[l];
		return;
	}
	int mid=(l+r)>>1;
	gz(ls,l,mid);
	gz(rs,mid+1,r);
	pushup(rt);
}

void fz(int L,int R,int F,int l,int r,int rt){
	if(L<=l&&r<=R){
		flazy(rt,l,r,F);
		return;
	}
	pushdown(rt,l,r);
	int mid=(l+r)>>1;
	if(L<=mid)fz(L,R,F,l,mid,ls);
	if(R>mid)fz(L,R,F,mid+1,r,rs);
	pushup(rt);
}

void jz(int L,int R,int C,int l,int r,int rt){
	if(L<=l&&r<=R){
		addlazy(rt,l,r,C);
		return;
	}
	pushdown(rt,l,r);
	int mid=(l+r)>>1;
	if(L<=mid)jz(L,R,C,l,mid,ls);
	if(R>mid)jz(L,R,C,mid+1,r,rs);
	pushup(rt);
}

int query(int L,int R,int l,int r,int rt){
	if(L>r||R<l)return 0;
	if(L<=l&&r<=R)return t[rt].x;
	pushdown(rt,l,r);
	int mid=(l+r)>>1;
	return max(query(L,R,l,mid,ls),query(L,R,mid+1,r,rs));
}

signed main(){
	cin>>n>>q;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	gz(1,1,n);
	while(q--){
		int op,l,r,x;
		cin>>op>>l>>r;
		if(op==1){
			cin>>x;
			fz(l,r,x,1,n,1);
		}else if(op==2){
			cin>>x;
			jz(l,r,x,1,n,1);
		}else{
			cout<<query(l,r,1,n,1)<<"\n";
		}
	}
}