#include<iostream>

 #include<cstdio>

 #include<cstring>

 #include<vector>

 #include<algorithm>

 #define lson l,m

 #define rson m+1,r

 using namespace std;

 const int MAXN=+;

 int n,q,tot,m,d;

 struct node

 {

     int l,r,k,Q;

 }op[MAXN];

 int a[MAXN<<],hash[MAXN<<],T[MAXN<<],S[MAXN<<],use[MAXN<<];

 int L[MAXN<<],R[MAXN<<],sum[MAXN<<];

 int lowbit(int x)

 {

     return (x&(-x));

 }

 int build(int l,int r)

 {

     int rt=++tot;

     sum[rt]=;

     if (l!=r)

     {

         int m=(l+r)>>;

         L[rt]=build(lson);

         R[rt]=build(rson);

     }

     return rt;

 }

 int update(int pre,int l,int r,int x,int op)

 {

     int rt=++tot;

     L[rt]=L[pre],R[rt]=R[pre],sum[rt]=sum[pre]+op;

     if (l<r)

     {

         int m=(l+r)>>;

         if (x<=m) L[rt]=update(L[pre],lson,x,op);

             else R[rt]=update(R[pre],rson,x,op);

     }

     return rt;

 }

 int Sum(int x)

 {

     int ret=;

     while (x>)

     {

         ret+=sum[L[use[x]]];

         x-=lowbit(x);

     }

     return ret;

 }

 int query(int Sl,int Sr,int Tl,int Tr,int l,int r,int k)

 {

     if (l==r) return l;

     int m=(l+r)>>;

     int tmp=Sum(Sr)-Sum(Sl)+sum[L[Tr]]-sum[L[Tl]];

     if (tmp>=k)

     {

         for (int i=Sl;i;i-=lowbit(i)) use[i]=L[use[i]];

         for (int i=Sr;i;i-=lowbit(i)) use[i]=L[use[i]];

         return query(Sl,Sr,L[Tl],L[Tr],lson,k);

     }

     else

     {

         for (int i=Sl;i;i-=lowbit(i)) use[i]=R[use[i]];

         for (int i=Sr;i;i-=lowbit(i)) use[i]=R[use[i]];

         return query(Sl,Sr,R[Tl],R[Tr],rson,k-tmp);

     }

 } 

 void modify(int x,int p,int delta)

 {

     while (x<=n)

     {

         S[x]=update(S[x],,d,p,delta);

         x+=lowbit(x);

     }

 }

 void init()

 {

     tot=;

     m=;

     d=;

     scanf("%d%d",&n,&q);

     for (int i=;i<=n;i++) scanf("%d",&a[i]),hash[++m]=a[i];

     for (int i=;i<q;i++)

     {

         char s[];

         scanf("%s",s);

         if (s[]=='Q')    scanf("%d%d%d",&op[i].l,&op[i].r,&op[i].k),op[i].Q=;

             else

             {

                 scanf("%d%d",&op[i].l,&op[i].r);

                 op[i].Q=;

                 hash[++m]=op[i].r;

             }

     }

     /*因为修改后的数可能不在初始几个数的范围内，故要先输入完查询*/ 

     sort(hash+,hash+m+);

     d=unique(hash+,hash++m)-hash-;

     T[]=build(,d);//T表示每一步T树的树根

     for (int i=;i<=n;i++)

     {

         int x=lower_bound(hash+,hash+d+,a[i])-hash;

         T[i]=update(T[i-],,d,x,);

     }

     for (int i=;i<=n;i++) S[i]=T[];

 }

 void solve()

 {

     for (int i=;i<q;i++)

     {

         if (op[i].Q)

         {

             for (int j=op[i].l-;j;j-=lowbit(j)) use[j]=S[j];

             for (int j=op[i].r;j;j-=lowbit(j)) use[j]=S[j];

             int ans=query(op[i].l-,op[i].r,T[op[i].l-],T[op[i].r],,d,op[i].k);

             printf("%d\n",hash[ans]);

         }

         else

         {

             int x=lower_bound(hash+,hash+d+,a[op[i].l])-hash;

             int y=lower_bound(hash+,hash+d+,op[i].r)-hash;

             modify(op[i].l,x,-);

             modify(op[i].l,y,);

             a[op[i].l] =op[i].r;

         }

     }

 }

 int main()

 {

     init();

     solve();

     return ;

 }