#include<cstdio>

 #include<string.h>

 using namespace std;

 int ans;

 int max1=;

 int a[];

 struct Node{

     int left;

     int right;

     int max;

 }node[];

 void TreeMake(int l,int r,int i)

 {

     node[i].left=l;

     node[i].right=r;

     node[i].max=;

     if(l==r)

     {

         node[i].max=a[l];//是a[l]!!!!!

         return;

     }

     else

     {

         int mid=(l+r)/;

         TreeMake(l,mid,*i);

         TreeMake(mid+,r,*i+);

         node[i].max=node[*i].max>node[*i+].max?node[*i].max:node[*i+].max;//注意更新最大值，回溯

     }

 }

 void Updata_tree(int l,int i)

 {

     if(node[i].left==l&&node[i].right==l)

     {

          node[i].max=ans;

          return;

     }

     else{

         int mid=(node[i].left+node[i].right)/;

         if(l<=mid) Updata_tree(l,*i);

         if(l>mid) Updata_tree(l,*i+);

         node[i].max=node[*i].max>node[*i+].max?node[*i].max:node[*i+].max;//注意回溯！！

     }

 }

 void Query_tree(int l,int r,int i)

 {

    //if(node[i].left==l&&node[i].right==r)

      //   return node[i].max;

    //

    if(node[i].left>=l&&node[i].right<=r)

    {

        if(max1<node[i].max)

             max1=node[i].max;

        return;

    }

    int mid=(node[i].left+node[i].right)/;

    if(r<=mid) Query_tree(l,r,*i);

    else if(l>mid) Query_tree(l,r,*i+);

    else

    {

        Query_tree(l,r,*i);

        Query_tree(l,r,*i+);

    }

 }

 int main()

 {

     int n,m;

     char ch[];

     while(scanf("%d %d",&n,&m)!=EOF)

     {

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

             scanf("%d",&a[i]);

             TreeMake(,n,);

         while(m--)

         {

             scanf("%s",ch);

             int x,y;

             scanf("%d %d",&x,&y);

             max1=;

             if(ch[]=='Q')

             {

                 Query_tree(x,y,);//查询(x,y)区间

                 printf("%d\n",max1);

             }

             if(ch[]=='U')

             {

                 ans=y;

                 Updata_tree(x,);

             }

         }

     }

     return ;

 }