#include<bits/stdc++.h>
#include<ctime>
#include<cstdlib>
using namespace std;
int random(int n){
	return (long long)rand()*rand()%n;
}
int main(){
	freopen("score1.in","w",stdout);
	srand((unsigned)time(0));
	int n=random(100000)+1;
	int m=random(100000)+1;
	cout<<n<<' '<<m<<'\n';
	for(int i=1;i<=n;i++){
		int a=random(101);
		cout<<a<<' ';
	}
	cout<<'\n';
	for(int i=1;i<=m;i++){
		int op=random(4)+1,x=random(n)+1,y=random(n)+1,c=random(10)+1;
		cout<<op<<' '<<x<<' ';
		if(op>2) cout<<y<<'\n';
		if(op==1) cout<<y<<' '<<c<<'\n';
		if(op==2) cout<<c<<'\n';
	}
}

#include<bits/stdc++.h>
#define int long long
#define mid ((l+r)>>1)
#define lt (root<<1)
#define rt (root<<1|1)
using namespace std;
const int N=1e5+5;
int n,m,a[N];
struct Node{
	int sum,maxx,minn,add,l,r;
}tree[N];
inline void pushup(int root){
	tree[root].sum=tree[lt].sum+tree[rt].sum;
	tree[root].maxx=max(tree[lt].maxx,tree[rt].maxx);
	tree[root].minn=min(tree[lt].minn,tree[rt].minn);
}
inline void pushdown(int root){
	if(tree[root].add){
		tree[lt].sum=tree[lt].sum+(tree[lt].r-tree[lt].l+1)*tree[root].add;
		tree[rt].sum=tree[rt].sum+(tree[rt].r-tree[rt].l+1)*tree[root].add;
		tree[lt].maxx+=tree[root].add;
		tree[lt].minn+=tree[root].add;
		tree[rt].maxx+=tree[root].add;
		tree[rt].minn+=tree[root].add;
		tree[lt].add+=tree[root].add;
		tree[rt].add+=tree[root].add;
	}
	tree[root].add=0;
}
inline void build(int root,int l,int r){
	tree[root].l=l;
	tree[root].r=r;
	if(l==r){
		tree[root].sum=tree[root].maxx=tree[root].minn=a[l];
		return;	
	}
	build(lt,l,mid);
	build(rt,mid+1,r);
	pushup(root);
}
inline void update(int root,int l,int r,int ql,int qr,int add){
	if(l>=ql&&r<=qr){
		tree[root].sum+=(r-l+1)*add;
		tree[root].maxx+=add;
		tree[root].minn+=add;
		tree[root].add+=add;
		return;
	}
	pushdown(root);
	if(ql<=mid) update(lt,l,mid,ql,qr,add);
	if(qr>mid) update(rt,mid+1,r,ql,qr,add);
	pushup(root);
}
inline void change(int root,int l,int r,int q,int add){
	if(l==r){
		tree[root].sum+=add;
		tree[root].maxx+=add;
		tree[root].minn+=add;
		return;
	}
	pushdown(root);
	if(q<=mid) change(lt,l,mid,q,add);
	else change(rt,mid+1,r,q,add);
	pushup(root);
}
inline int query_max(int root,int l,int r,int ql,int qr){
	if(l>=ql&&r<=qr) return tree[root].maxx;
	pushdown(root);
	int res=LONG_LONG_MIN;
	if(ql<=mid) res=max(res,query_max(lt,l,mid,ql,qr));
	if(qr>mid) res=max(res,query_max(rt,mid+1,r,ql,qr));
	pushup(root);
	return res;
}
inline int query_min(int root,int l,int r,int ql,int qr){
	if(l>=ql&&r<=qr) return tree[root].minn;
	pushdown(root);
	int res=LONG_LONG_MAX;
	if(ql<=mid) res=min(res,query_min(lt,l,mid,ql,qr));
	if(qr>mid) res=min(res,query_min(rt,mid+1,r,ql,qr));
	pushup(root);
	return res;
}
inline int query_sum(int root,int l,int r,int ql,int qr){
	if(l>=ql&&r<=qr) return tree[root].sum;
	pushdown(root);
	int res=0;
	if(ql<=mid) res+=query_sum(lt,l,mid,ql,qr);
	if(qr>mid) res+=query_sum(rt,mid+1,r,ql,qr);
	pushup(root);
	return res;
}
signed main(){
	freopen("score1.in","r",stdin);
	freopen("score1.out","w",stdout);
	scanf("%lld%lld",&n,&m);
	for(int i=1;i<=n;i++) scanf("%lld",a+i);
	build(1,1,n);
	while(m--){
		int op,x,y,c;
		scanf("%lld",&op);
		if((op&1)&&!(op&2)){
			scanf("%lld%lld%lld",&x,&y,&c);
			if(x>y) swap(x,y);
			update(1,1,n,x,y,c);
		}
		if(!(op&1)&&(op&2)){
			scanf("%lld%lld",&x,&c);
			change(1,1,n,x,c);
		}
		if((op&1)&&(op&2)){
			scanf("%lld%lld",&x,&y);
			if(x>y) swap(x,y);
			long double ans=query_sum(1,1,n,x,y)*1.0/(1.0*(y-x+1));
			printf("%.2Lf\n",ans);
		}
		if(!(op&1)&&!(op&2)){
			scanf("%lld%lld",&x,&y);
			if(x>y) swap(x,y);
			printf("%lld\n",query_max(1,1,n,x,y)-query_min(1,1,n,x,y));
		}
	}
}