#include<bits/stdc++.h>
using namespace std;
#define ll long long
struct tree{
	ll l,r,maxi,mini,sumi,lazy_1=0,lazy_2=1,lazy_3;
	bool flag=0;
	tree *left=NULL,*right=NULL;
};
ll a[5114514],n,m;
tree *top;
ll read(){
	char c=getchar();
	while(c==' ' || c=='\n')c=getchar();
	if(c=='-'){
		return -read();
	}ll x=0;
	while(c!=' ' && c!='\n'){
		x=(x<<3)+(x<<1)+c-48;
		c=getchar();
	}return x;
}void paint(ll x){
	if(x<0){
		putchar('-');
		x=-x;
	}if(x>9){
		paint(x/10);
		x%=10;
	}putchar(x+48);
}
tree* build(ll l,ll r){
	tree *x=new tree;
	x->l=l;
	x->r=r;
	if(l==r){
		x->maxi=x->mini=x->sumi=a[l];
		return x;
	}x->left=build(l,(l+r)>>1);
	x->right=build(((l+r)>>1)+1,r);
	x->maxi=max(x->left->maxi,x->right->maxi);
	x->mini=min(x->left->mini,x->right->mini);
	x->sumi=x->left->sumi+x->right->sumi;
	return x;
}void add(tree *x,ll v){
	x->lazy_1+=v;
	x->maxi+=v;
	x->mini+=v;
	x->sumi+=v*(x->r-x->l+1);
}void mul(tree *x,ll v){
	x->lazy_1*=v;
	x->lazy_2*=v;
	x->maxi*=v;
	x->mini*=v;
	x->sumi*=v;
}void change(tree *x,ll v){
	x->lazy_1=0;
	x->lazy_2=0;
	x->lazy_3=v;
	x->flag=1;
	x->maxi=v;
	x->mini=v;
	x->sumi=v*(x->r-x->l+1);
}void pushdown(tree *x){
	if(x->left==NULL){
		return;
	}if(x->flag==1){
		change(x->left,x->lazy_3);
		change(x->right,x->lazy_3);
		x->flag=0;
	}if(x->lazy_2>1){
		mul(x->left,x->lazy_2);
		mul(x->right,x->lazy_2);
		x->lazy_2=1;
	}if(x->lazy_1!=0){
		add(x->left,x->lazy_1);
		add(x->right,x->lazy_1);
		x->lazy_1=0;
	}
}void date_add(tree *x,ll l,ll r,ll v){
	if(x->l>=l && x->r<=r){
		add(x,v);
		return;
	}pushdown(x);
	if(x->left->l<=r && x->left->r>=l){
		date_add(x->left,l,r,v);
	}if(x->right->l<=r && x->right->r>=l){
		date_add(x->right,l,r,v);
	}x->sumi=x->left->sumi+x->right->sumi;
	x->maxi=max(x->left->maxi,x->right->maxi);
	x->mini=min(x->left->mini,x->right->mini);
}void date_mul(tree *x,ll l,ll r,ll v){
	if(x->l>=l && x->r<=r){
		mul(x,v);
		return;
	}pushdown(x);
	if(x->left->l<=r && x->left->r>=l){
		date_mul(x->left,l,r,v);
	}if(x->right->l<=r && x->right->r>=l){
		date_mul(x->right,l,r,v);
	}x->sumi=x->left->sumi+x->right->sumi;
	x->maxi=max(x->left->maxi,x->right->maxi);
	x->mini=min(x->left->mini,x->right->mini);
}void date_change(tree *x,ll l,ll r,ll v){
	if(x->l>=l && x->r<=r){
		change(x,v);
		return;
	}pushdown(x);
	if(x->left->l<=r && x->left->r>=l){
		date_change(x->left,l,r,v);
	}if(x->right->l<=r && x->right->r>=l){
		date_change(x->right,l,r,v);
	}x->sumi=x->left->sumi+x->right->sumi;
	x->maxi=max(x->left->maxi,x->right->maxi);
	x->mini=min(x->left->mini,x->right->mini);
}ll query_max(tree *x,ll l,ll r){
	if(x->l>=l && x->r<=r){
		return x->maxi;
	}pushdown(x);
	ll maxi=-1145141919810;
	if(x->left->l<=r && x->left->r>=l){
		maxi=max(maxi,query_max(x->left,l,r));
	}if(x->right->l<=r && x->right->r>=l){
		maxi=max(maxi,query_max(x->right,l,r));
	}return maxi;
}ll query_min(tree *x,ll l,ll r){
	if(x->l>=l && x->r<=r){
		return x->mini;
	}pushdown(x);
	ll mini=1145141919810;
	if(x->left->l<=r && x->left->r>=l){
		mini=min(mini,query_min(x->left,l,r));
	}if(x->right->l<=r && x->right->r>=l){
		mini=min(mini,query_min(x->right,l,r));
	}return mini;
}ll query_sum(tree *x,ll l,ll r){
	if(x->l>=l && x->r<=r){
		return x->sumi;
	}pushdown(x);
	ll sumi=0;
	if(x->left->l<=r && x->left->r>=l){
		sumi+=query_sum(x->left,l,r);
	}if(x->right->l<=r && x->right->r>=l){
		sumi+=query_sum(x->right,l,r);
	}return sumi;
}int main(){
	n=read();
	m=read();
	for(ll i=1;i<=n;i++){
		a[i]=read();
	}top=build(1,n);
	for(ll i=1;i<=m;i++){
		ll op;
		op=read();
		if(op==3){
			ll x=read(),y=read();
			paint(query_max(top,x,y));
			putchar('\n');
		}if(op==2){
			ll x=read(),y=read(),z=read();
			date_add(top,x,y,z);
		}if(op==1){
			ll x=read(),y=read(),z=read();
			date_change(top,x,y,z);
		}
	}
    return 0;
}

未知错误，本地通过，在线IDE通过