#include<bits/stdc++.h>
#define l(p) t[p].l
#define r(p) t[p].r
#define m(p) t[p].m
#define pdj(p) t[p].pdj
#define pdg(p) t[p].pdg
#define N 10000005
#define inf 1054114514
using namespace std;
long long n,m,typ,x,y,k,a[N];
struct xds
{
	long l;//左 
	long r;//右 
	long m;//最大值 
	long pdj;//判断加 
	long pdg;//判断改 
}t[N*4];
void bui(long long x,long long y,long long p)
{
	l(p)=x;r(p)=y;pdj(p)=0;pdg(p)=inf;
	if(x==y)
	{m(p)=a[x];return;}
	long long mid=(x+y)>>1;
	bui(x,mid,p*2);
	bui(mid+1,y,p*2+1);
	m(p)=max(m(p*2),m(p*2+1));
}
void bj(long long p)
{
	if(pdg(p)!=inf)
	{
		pdg(p*2)=pdg(p);
		pdg(p*2+1)=pdg(p);
		m(p*2)=pdg(p);
		m(p*2+1)=pdg(p);
		pdg(p)=inf;
	}
	else if(pdj(p)!=0)
	{
		pdj(p*2)+=pdj(p);
		pdj(p*2+1)+=pdj(p);
		m(p*2)+=pdj(p);
		m(p*2+1)+=pdj(p);
		pdj(p)=0;
	}
}
void xg(long long x,long long y,long long k,long long p)
{
	if(l(p)>=x&&r(p)<=y)
	{m(p)=k;pdj(p)=0;pdg(p)=k;return;}
	bj(p);
	long long mid=(l(p)+r(p))>>1;
	if(x<=mid)
	xg(x,y,k,p*2);
	if(y>mid)
	xg(x,y,k,p*2+1);
	m(p)=max(m(p*2),m(p*2+1));
}
void zj(long long x,long long y,long long k,long long p)
{
	if(l(p)>=x&&r(p)<=y)
	{
		m(p)+=k;
		if(pdg(p)!=inf)
		pdg(p)+=k;
		else
		pdj(p)+=k;
		return;
	}
	bj(p);
	long long mid=(l(p)+r(p))>>1;
	if(x<=mid)
	zj(x,y,k,p*2);
	if(y>mid)
	zj(x,y,k,p*2+1);
	m(p)=max(m(p*2),m(p*2+1));
}
long long cx(long long x,long long y,long long p)
{
	if(l(p)>=x&&r(p)<=y)
	return m(p);
	bj(p);
	long long mid=(l(p)+r(p))>>1;
	long long val=-2099999999;
	if(x<=mid)
	val=max(val,cx(x,y,p*2));
	if(y>mid)
	val=max(val,cx(x,y,p*2+1));
	return val;
}
int main()
{
	scanf("%lld%lld",&n,&m);
	for(int i=1;i<=n;i++)
	scanf("%lld",&a[i]);
	bui(1,n,1);
	for(int i=1;i<=m;i++)
	{
		scanf("%lld%lld%lld",&typ,&x,&y);
		switch(typ)
		{
			case 1:
				scanf("%lld",&k);
				xg(x,y,k,1);
				break;
			case 2:
				scanf("%lld",&k);
				zj(x,y,k,1);
				break;
			case 3:
				printf("%lld\n",cx(x,y,1));
				break;	
		}
	}
	return 0;
}