#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e6+10,N=-1e9-10;
int a[maxn],sum[maxn<<2],tagA[maxn<<2],tagP[maxn<<2];
int sl(int rt){
	return rt<<1;
}
int sl2(int rt){
	return rt<<1|1;
}
void Push_Up(int rt){
	sum[rt] = max(sum[sl(rt)],sum[sl2(rt)]);
}
void BuildTree(int rt,int l,int r){
	tagA[rt] = N;
	if(l == r){
		sum[rt] = a[l];
		return;
	}
	int mid = (l+r)>>1;
	BuildTree(sl(rt),l,mid);
	BuildTree(sl2(rt),mid+1,r);
	Push_Up(rt);
}
void lazytagA(int rt,int d){//xiugai
	tagA[rt] = d;
	sum[rt] = d;
	tagP[rt] =d;
}
void lazytagP(int rt,int d){//jia
	tagP[rt] +=d;
	sum[rt] +=d;
}
void pushdownA(int rt){//xiugai
	if(sum[rt] != N){
		lazytagA(sl(rt),tagA[rt]);
		lazytagA(sl2(rt),tagA[rt]);
	}
	tagA[rt] = N;
}
void pushdownB(int rt){//jia
	if(tagP[rt]){
		lazytagP(sl(rt),tagP[rt]);
		lazytagP(sl2(rt),tagP[rt]);
	}
	tagP[rt] = 0;
}
void updateA(int rt,int l,int r,int L,int R,int d){//xiuagi
	if(L<=l && R>=r){
		lazytagA(rt,d);
		return;
	}
	pushdownA(rt);
	pushdownB(rt);
	int mid = (l+r)>>1;
	if(l<=mid){
		updateA(rt<<1,l,mid,L,R,d);
	}
	if(R>mid){
		updateA(rt<<1|1,mid+1,r,L,R,d);
	}
	Push_Up(rt);
}
void updateP(int rt,int l,int r,int L,int R,int d){//jia
	if(L<=l && R>=r){
		lazytagP(rt,d);
		return;
	}
	pushdownA(rt);
	pushdownB(rt);
	int mid=(l+r)>>1;
	if(L<=mid)
		updateP(rt<<1,l,mid,L,R,d);
	if(R>mid)
		updateP(rt<<1|1,mid+1,r,L,R,d);
	Push_Up(rt);
}
int ask(int rt,int l,int r,int L,int R){
	if(L<=l && R<=r){
		return sum[rt];
	}
	pushdownA(rt);
	pushdownB(rt);
	int LLRR=-114514514;
	int mid = (l+r)>>1;
	if(L<=mid) LLRR = max(LLRR,ask(rt<<1,l,mid,L,R));
	if(R>mid) LLRR = max(LLRR,ask(rt<<1|1,mid+1,r,L,R));
	return LLRR;
}
int main(){
	int n,m,op=0,l,r,d;
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;++i){
		scanf("%d",&a[i]);
	}
	BuildTree(1,1,n);
	for(int i=1;i<=m;++i){
		scanf("%d",&op);
		if(op == 1){
			scanf("%d%d%d",&l,&r,&d);
			updateA(1,1,n,l,r,d);
		}
		if(op == 2){
			scanf("%d%d%d",&l,&r,&d);
			updateP(1,1,n,l,r,d);
		}
		if(op == 3){
			scanf("%d%d",&l,&r);
			printf("%d\n",ask(1,1,n,l,r));
		}
	}
	return 0;
}