#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e6 + 5;
const ll INF = 0x7fffffffffffffff;
int a[N];
ll d[N * 4],b[N * 4],c[N * 4];
bool v[N * 4];
inline void up(int p){d[p] = max(d[p * 2],d[p * 2 + 1]);}
void pd(int l,int r,int p){
	if (v[p]){
		d[p * 2] = b[p] + c[p],d[p * 2 + 1] = b[p] + c[p];
		b[p * 2] = b[p],b[p * 2 + 1] = b[p];
		c[p * 2] = c[p],c[p * 2 + 1] = c[p];
		v[p * 2] = v[p],v[p * 2 + 1] = v[p];
		v[p] = 0;
	}else{
		d[p * 2] += b[p],d[p * 2 + 1] += b[p];
		b[p * 2] += b[p],b[p * 2 + 1] += b[p];
	}
	b[p] = 0;
}
void build(int l,int r,int p){
	d[p] = -INF;
	if (l == r){
		d[p] = a[l];
// printf("%d:%d %d\n",l,p,d[p]);
		return ;
	}
	int mid = l + (r - l >> 1);
	build(l,mid,p * 2);
	build(mid + 1,r,p * 2 + 1);
	up(p);
}
void add(int tl,int tr,int l,int r,int p,ll x){
	if (tl <= l && r <= tr){
		d[p] += x;
		b[p] += x;
// printf(" %d %d %d %d %d\n",p,d[p],b[p],c[p],v[p]);
		return ;
	}
	pd(l,r,p);
	int mid = l + (r - l >> 1);
	if (tl <= mid)	add(tl,tr,l,mid,p * 2,x);
	if (mid < tr)	add(tl,tr,mid + 1,r,p * 2 + 1,x);
	up(p);
// printf(" %d %lld %d %d %d\n",p,d[p],b[p],c[p],v[p]);
}
void mod(int tl,int tr,int l,int r,int p,ll x){
	if (tl <= l && r <= tr){
		d[p] = x;
		c[p] = x;
		v[p] = 1;
		b[p] = 0;
// printf(" %d %lld %d %d %d\n",p,d[p],b[p],c[p],v[p]);
		return ;
	}
	pd(l,r,p);
	int mid = l + (r - l >> 1);
	if (tl <= mid)	mod(tl,tr,l,mid,p * 2,x);
	if (mid < tr)	mod(tl,tr,mid + 1,r,p * 2 + 1,x);
	up(p);
// printf(" %d %lld %d %d %d\n",p,d[p],b[p],c[p],v[p]);
}
ll query(int tl,int tr,int l,int r,int p){
	if (l == r)	return d[p];
	pd(l,r,p);
	int mid = l + (r - l >> 1);
	ll mx = -INF;
	if (tl <= mid)	mx = max(mx,query(tl,tr,l,mid,p * 2));
	if (mid < tr)	mx = max(mx,query(tl,tr,mid + 1,r,p * 2 + 1));
	return mx;
}
int main(int argc, char **argv){
	// freopen("C:/Users/Administrator/Downloads/P1253_5.in","r",stdin);
	// freopen("C:/Users/Administrator/Downloads/P1253_5.ans","w",stdout);
	int n,q;
	scanf("%d %d",&n,&q);
	for (int i = 1;i <= n;i++){
		scanf("%d",a + i);
	}
	build(1,n,1);
	while (q--){
		int op,l,r;
		scanf("%d %d %d",&op,&l,&r);
		if (op == 1){
			ll x;
			scanf("%lld",&x);
			mod(l,r,1,n,1,x);
		}else if (op == 2){
			ll x;
			scanf("%lld",&x);
			add(l,r,1,n,1,x);
		}else{
			printf("%lld\n",query(l,r,1,n,1));
		}
	}
	return 0;
}
/*
           1
     2           3
  4     5     6     7
8   9 10 11 12 13 14 15
1   2   3   04 05   6
*/