#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>

#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <vector>
#include <iostream>
#include <queue>

using namespace std;

#define maxn 20005
#define mlog 16
#define inf (0x3f3f3f3f)

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*10+ch-'0'; ch=getchar();}
    return x*f;
}

int rt[maxn],ls[maxn*mlog*mlog],rs[maxn*mlog*mlog],siz[maxn*mlog*mlog];
int a[maxn],b[maxn],n,m,top=0,tot=0;
int opt[maxn],x[maxn],y[maxn],z[maxn],L[mlog],R[mlog];
char s[11];

void ins(int o1,int & o2,int l,int r,int x,int f)
{
//  printf("ins %d %d %d %d %d %d\n",o1,o2,l,r,x,f);
    o2=++tot;
    siz[o2]=siz[o1]+f;
    if (l==r) return ;
    int mid=(l+r)/2;
    if (x<=mid) rs[o2]=rs[o1],ins(ls[o1],ls[o2],l,mid,x,f);
    else ls[o2]=ls[o1],ins(rs[o1],rs[o2],mid+1,r,x,f);
    return ;
}

int query(int l,int r,int x)
{
//  printf("query %d %d %d\n",l,r,x);
    if (l==r) return l;
    int mid=(l+r)/2,tmp=0;
    for (int i=1;i<=L[0];++i) tmp-=siz[ls[L[i]]];
    for (int i=1;i<=R[0];++i) tmp+=siz[ls[R[i]]];
//  printf("tmp is %d\n",tmp);
    if (x<=tmp)
    {
        for (int i=1;i<=L[0];++i) L[i]=ls[L[i]];
        for (int i=1;i<=R[0];++i) R[i]=ls[R[i]];
        return query(l,mid,x);
    }
    else
    {
        for (int i=1;i<=L[0];++i) L[i]=rs[L[i]];
        for (int i=1;i<=R[0];++i) R[i]=rs[R[i]];
        return query(mid+1,r,x-tmp);
    }
}

int main()
{
    top=n=read();m=read();
    for (int i=1;i<=n;++i) b[i]=a[i]=read();
    for (int i=1;i<=m;++i)
    {
        scanf("%s",s);
        switch(s[0])
        {
            case 'Q': opt[i]=0;x[i]=read();x[i]--;y[i]=read();z[i]=read();break;
            case 'C': opt[i]=1;x[i]=read();y[i]=read();b[++top]=y[i];break;
        }
    }
    sort(b+1,b+top+1);
    top=unique(b+1,b+top+1)-b-1;
    for (int i=1;i<=n;++i) a[i]=lower_bound(b+1,b+top+1,a[i])-b;
    for (int i=1;i<=m;++i) if (opt[i]) y[i]=lower_bound(b+1,b+top+1,y[i])-b;
//  printf("lisan is OK!\n");
//  for (int i=1;i<=n;++i) printf("%d ",a[i]); printf("\n");
//  for (int i=1;i<=m;++i) printf("%d ",y[i]); printf("\n");
    for (int i=1;i<=n;++i)
    {
//      printf("ins %d %d\n",a[i],i);getchar();
        for (int j=i;j<=n;j+=j&(-j))
            ins(rt[j],rt[j],1,top,a[i],1);
    }
    for (int i=1;i<=m;++i)
    {
        if (opt[i])
        {
//          printf("fix %d to %d\n",x[i],y[i]);
            for (int j=x[i];j<=n;j+=j&(-j))
            {
                ins(rt[j],rt[j],1,top,a[x[i]],-1);
                ins(rt[j],rt[j],1,top,y[i],1);
            }
            a[x[i]]=y[i];
        }
        else
        {
//          printf("query %d %d %d \n",x[i],y[i],z[i]);
            L[0]=0; R[0]=0;
            for (int j=x[i];j;j-=j&(-j)) L[++L[0]]=rt[j];
            for (int j=y[i];j;j-=j&(-j)) R[++R[0]]=rt[j];
//          printf("L :"); for (int j=1;j<=L[0];++j) printf("%d ",L[i]);
//          printf("R :"); for (int j=1;j<=R[0];++j) printf("%d ",R[i]);
            printf("%d\n",b[query(1,top,z[i])]);
        }
    }
}