#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll maxn = 1e6+10;
#define  inf 1e18

ll n,p;
ll a[maxn];
ll tr[4*maxn],laz[4*maxn],laz2[4*maxn];

inline ll read()
{
    ll x=0,f=1;char ch=getchar();
    while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}
    while (isdigit(ch)){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}

void build(ll k,ll l,ll r){
	if(l==r)
	{ 
		tr[k] = a[l];
		laz2[k] = -1145141919180;
		laz[k] = 0;
		return;
	}
	
	ll mid = (l+r) / 2;
	build(k*2,l,mid);
	build(k*2+1,mid+1,r);
	tr[k] = max(tr[k*2],tr[k*2+1]);
}

void cdown(ll k,ll l,ll r){ 
	if(laz2[k] != inf)
	 {
	 	laz[k*2] = laz[k*2+1] = 0;
		laz2[k*2] = laz2[k*2+1] = laz2[k];
		tr[k*2] = tr[k*2+1] = laz2[k];
		
		laz2[k] = inf; 
	 }
}

void sdown(ll k,ll l,ll r){
	if(laz[k])
	{
	 	cdown(k,l,r);
	 	laz[k*2] += laz[k];
	 	laz[k*2+1] += laz[k];
	 	tr[k*2] += laz[k];
	 	tr[k*2+1] += laz[k];
	 	laz[k] = 0;
	}
}

void pushdown(ll k,ll l,ll r){
	 cdown(k,l,r);
	 sdown(k,l,r);
}

ll query(ll k,ll l,ll r,ll x,ll y){
	if(x<=l && r<=y)	
		return tr[k];
	
	pushdown(k,l,r);
	ll mid = (l+r)/2;
	ll res  = -inf;
	if(x<=mid)	res = max(res,query(k*2,l,mid,x,y));
	if(mid+1<=y)	res = max(res,query(k*2+1,mid+1,r,x,y));
	 
	return res;
}

void modify1(ll k,ll l,ll r,ll x,ll y,ll z){
	if(x<=l && r<=y)
	{
		laz[k] = 0;
		tr[k] = laz2[k] = z;
		return;
	}
	
	pushdown(k,l,r);
	ll mid = (l+r) / 2;
	if(x<=mid)	modify1(k*2,l,mid,x,y,z);
	if(mid<y)	modify1(k*2+1,mid+1,r,x,y,z);
	tr[k] = max(tr[k*2],tr[k*2+1]);
}

void modify2(ll k,ll l,ll r,ll x,ll y,ll z){
	if(x<=l && r<=y)
	{
		cdown(k,l,r);
		laz[k] += z;
		tr[k] +=z;
		return;
	}
	
	pushdown(k,l,r);
	ll mid = (l+r)/2;
	if(x<=mid)	modify2(k*2,l,mid,x,y,z);
	if(mid<y)	modify2(k*2+1,mid+1,r,x,y,z);
	tr[k] = max(tr[k*2],tr[k*2+1]);
}

int main(){
	scanf("%lld%lld",&n,&p);
	for(ll i=1;i<=n;++i)
		a[i] = read();
	build(1,1,n);
	for(ll i=1;i<=4*n;++i)
		laz2[i] = inf;
		
	while(p--) 
	{
		ll f,x,y;
		f=read(),x=read(),y=read();
		//cout << f << " " << x << " " << y << endl;
		 if(f==1)
		{
			ll z=read();
			modify1(1,1,n,x,y,z); 
		}
		else if(f==2){
			ll z=read();
			modify2(1,1,n,x,y,z);
		}
		else
		{	
			//cout << "asdchaoiunc" << endl;
			printf("%lld\n",query(1,1,n,x,y));
		}
		
	}
	return 0;
}