void up(int x){if(x){size[x]=cnt[x];//我TM这行忘了if(son[x][0])size[x]+=size[son[x][0]];if(son[x][1])size[x]+=size[son[x][1]];}}

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
const int N=4000005,inf=1e9;
int n,m,a[N];int root[N],son[N][3],fa[N],key[N],size[N],type,cnt[N];void clear(int x){if(!x)return ;fa[x]=cnt[x]=son[x][0]=son[x][1]=size[x]=key[x]=0;}int pre(int k){int now=son[root[k]][0];while(son[now][1])now=son[now][1];return now;}bool judge(int x){return son[fa[x]][1]==x;}void up(int x){if(x){size[x]=cnt[x];if(son[x][0])size[x]+=size[son[x][0]];if(son[x][1])size[x]+=size[son[x][1]];}}void rotate(int x){int old=fa[x],oldf=fa[old],lr=judge(x);son[old][lr]=son[x][lr^1];fa[son[old][lr]]=old;son[x][lr^1]=old;fa[old]=x;fa[x]=oldf;if(oldf)son[oldf][son[oldf][1]==old]=x;up(old);up(x);}void splay(int k,int x){for(int f;f=fa[x];rotate(x))if(fa[f])rotate(judge(x)==judge(f)?f:x);root[k]=x;}void ins(int k,int x){if(!root[k]){type++;key[type]=x;root[k]=type;cnt[type]=size[type]=1;fa[type]=son[type][0]=son[type][1]=0;return ;}int now=root[k],f=0;while(1){if(x==key[now]){cnt[now]++;up(now);up(f);splay(k,now);return ;}f=now;now=son[now][key[now]<x];if(!now){type++;size[type]=cnt[type]=1;son[type][0]=son[type][1]=0;son[f][x>key[f]]=type;fa[type]=f;key[type]=x;up(f);splay(k,type);return ;}}}int getrank(int k,int x){int now=root[k],ans=0;while(1){if(!now)return ans;if(x==key[now])return (son[now][0]?size[son[now][0]]:0)+ans;else if(x>key[now]){ans+=(son[now][0]?size[son[now][0]]:0)+cnt[now];now=son[now][1];}else if(x<key[now])now=son[now][0];}}int findpos(int k,int x){int now=root[k];while(1){if(x==key[now])return now;else if(x<key[now])now=son[now][0];else now=son[now][1];}}int findpre(int k,int x){int now=root[k],ans=0;while(now){if(key[now]<x){if(ans<key[now])ans=key[now];now=son[now][1];}else now=son[now][0];}return ans;}int findnxt(int k,int x){int now=root[k],ans=inf;while(now){if(key[now]>x){if(ans>key[now])ans=key[now];now=son[now][0];}else now=son[now][1];}return ans;}void del(int k,int x){int now=findpos(k,x);splay(k,now);if(cnt[root[k]]>1){cnt[root[k]]--;up(root[k]);return ;}else if(!son[root[k]][0]&&(!son[root[k]][1])){clear(root[k]);root[k]=0;return ;}int old=root[k];if(son[root[k]][0]*son[root[k]][1]==0){if(!son[root[k]][0])root[k]=son[root[k]][1];else root[k]=son[root[k]][0];fa[root[k]]=0;clear(old);return ;}int L=pre(k);splay(k,L);son[root[k]][1]=son[old][1];fa[son[old][1]]=root[k];clear(old);up(root[k]);}#define ls(k) k<<1#define rs(k) k<<1|1void update(int k,int l,int r,int pos,int val){ins(k,val);if(l==r)return ;int mid=l+r>>1;if(pos<=mid)update(ls(k),l,mid,pos,val);else update(rs(k),mid+1,r,pos,val);return ;}int rank(int k,int l,int r,int L,int R,int val){if(l>=L&&r<=R){int res=getrank(k,val);return res;}int mid=l+r>>1,res=0;if(L<=mid)res+=rank(ls(k),l,mid,L,R,val);if(R>mid)res+=rank(rs(k),mid+1,r,L,R,val);return res;}void modify(int k,int l,int r,int pos,int val){del(k,a[pos]);ins(k,val);if(l==r)return ;int mid=l+r>>1;if(pos<=mid)modify(ls(k),l,mid,pos,val);else modify(rs(k),mid+1,r,pos,val);}int getpre(int k,int l,int r,int L,int R,int val){if(l>=L&&r<=R)return findpre(k,val);int mid=l+r>>1,res=0;if(L<=mid)res=max(res,getpre(ls(k),l,mid,L,R,val));if(R>mid)res=max(res,getpre(rs(k),mid+1,r,L,R,val));return res;}int getnxt(int k,int l,int r,int L,int R,int val){if(l>=L&&r<=R)return findnxt(k,val);int mid=l+r>>1,res=inf;if(L<=mid)res=min(res,getnxt(ls(k),l,mid,L,R,val));if(R>mid)res=min(res,getnxt(rs(k),mid+1,r,L,R,val));return res;}
inline int read()
{int x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+ch-'0';ch=getchar();}return x*f;
}
int main()
{n=read();m=read();int op,maxx=0;for(int i=1;i<=n;i++){a[i]=read();update(1,1,n,i,a[i]);maxx=max(maxx,a[i]);}while(m--){op=read();if(op==1){int l=read(),r=read(),val=read();printf("%d\n",rank(1,1,n,l,r,val)+1);}else if(op==2){int l=read(),r=read(),val=read();int L=0,R=maxx+1;while(L!=R){int mid=L+R>>1;int res=rank(1,1,n,l,r,mid);//cout<<"***"<<res<<endl;if(res<val)L=mid+1;else R=mid;}printf("%d\n",L-1);}else if(op==3){int pos=read(),val=read();modify(1,1,n,pos,val);a[pos]=val;maxx=max(maxx,val);}else if(op==4){int l=read(),r=read(),val=read();printf("%d\n",getpre(1,1,n,l,r,val));}else if(op==5){int l=read(),r=read(),val=read();printf("%d\n",getnxt(1,1,n,l,r,val));}}return 0;
}