rt

#include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define pb push_back
#define pf push_front
#define pob pop_back
#define pof pop_front
#define pii pair<int,int>
#define pli pair<ll,int>
#define pll pair<ll,ll>
#define pil pair<int,ll>
#define fi first
#define se second
using namespace std;
inline ll read(){
	ll k=0,flag=1;
	char c=getchar();
	while(c<'0'||c>'9'){
		if(c=='-')flag=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9'){
		k=(k<<1)+(k<<3)+(c^48);
		c=getchar();
	}
	return k*flag;
}
inline void print(ll x){
    if(x<0){
        putchar('-');
        x=-x;
    }
    ll y=10,len=1;
    while(y<=x){
        y=(y<<1)+(y<<3);
        len++;
    }
    while(len--){
        y/=10;
        putchar(x/y+48);
        x%=y;
    }
}
inline char readc(){
	char c=getchar();
	while(c==' '||c=='\n')c=getchar();
	return c;
}
const int N=1e6+10;
int n,q;
ll a[N];
struct node{
	int l,r;
	ll ma,tag,ta;
}tree[N<<2];
void build(int i,int l,int r){
	tree[i].l=l;
	tree[i].r=r;
	if(l==r){
		tree[i].ma=a[l];
		return ;
	}
	int mid=l+r>>1;
	build(i<<1,l,mid);
	build(i<<1|1,mid+1,r);
	tree[i].ma=max(tree[i<<1].ma,tree[i<<1|1].ma);
	return ;
}
void pushdown(int i){
	if(tree[i].tag){
		tree[i<<1].tag+=tree[i].tag;
		tree[i<<1|1].tag+=tree[i].tag;
		tree[i<<1].ma+=tree[i].tag;
		tree[i<<1|1].ma+=tree[i].tag;
		tree[i].tag=0;
	}
	return ;
}
inline void change(int i,int l,int r,ll k){
	if(l<=tree[i].l&&tree[i].r<=r){
		tree[i].ma=tree[i<<1].ma=tree[i<<1|1].ma=k;
		return ;
	}
	int mid=tree[i].l+tree[i].r>>1;
	if(l<=mid)change(i<<1,l,r,k);
	if(mid+1<=r)change(i<<1|1,l,r,k);
	tree[i].ma=max(tree[i<<1].ma,tree[i<<1|1].ma);
	return ;
}
inline void add(int i,int l,int r,ll k){
	if(l<=tree[i].l&&tree[i].r<=r){
		tree[i].tag+=k;
		tree[i].ma+=k;
		return ;
	}
	pushdown(i);
	int mid=tree[i].l+tree[i].r>>1;
	if(l<=mid)add(i<<1,l,r,k);
	if(mid+1<=r)add(i<<1|1,l,r,k);
	tree[i].ma=max(tree[i<<1].ma,tree[i<<1|1].ma);
	return ;
}
inline ll query(int i,int l,int r){
	if(l<=tree[i].l&&tree[i].r<=r)return tree[i].ma;
	pushdown(i);
	int mid=tree[i].l+tree[i].r>>1;
	ll res=-1e18;
	if(l<=mid)res=max(res,query(i<<1,l,r));
	if(mid+1<=r)res=max(res,query(i<<1|1,l,r));
	return res;
}
int main(){
	cin>>n>>q;
	for(int i=1;i<=n;++i)a[i]=read();
	build(1,1,n);
	while(q--){
		int op=read(),l=read(),r=read();
		if(op==1){
			ll k=read();
			change(1,l,r,k);
		}
		if(op==2){
			ll k=read();
			add(1,l,r,k);
		}
		if(op==3){
			print(query(1,l,r));
			putchar('\n');
		}
	}
	return 0;
}