#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;

int max(int a,int b)
{
    return (a>b?a:b);
}
int a[200000];
struct Node
{
    int left,right;
    int t;
}node[4*200000];

void MakeTree(int l,int r,int i)
{
  node[i].left=l;
  node[i].right=r;

   if(l==r)
   {
       node[i].t=a[l];
       return ;
   }
  int mid=(l+r)/2;
  MakeTree(l,mid,2*i);
  MakeTree(mid+1,r,2*i+1);
  node[i].t=max(node[2*i].t,node[2*i+1].t);
}

void UpdateTree(int i,int x,int y)
{
    int l=node[i].left;
    int r=node[i].right;
    int mid=(l+r)/2;

    if(x==l&&x==r)
    {
        node[i].t=y;
        return ;
    }
    if(x>mid)
        UpdateTree(2*i+1,x,y);
    else
        UpdateTree(2*i,x,y);

    node[i].t=max(node[2*i].t,node[2*i+1].t);
}

int QueryTree(int x,int y,int i)
{
    if(node[i].left==x && node[i].right==y)
        return node[i].t;
    //if(node[i].left==node[i].right)
        //return 0;
    int m=(node[i].left+node[i].right)/2;

    if(x>m)
        return QueryTree(x,y,2*i+1);
    else if(y<=m)
        return QueryTree(x,y,2*i);
    else
        return  max(QueryTree(x,m,2*i),QueryTree(m+1,y,2*i+1));
}

int main ()
{
    int T,n,m;
    int i,j,x,y;
    char c[10];
    while(~scanf("%d%d",&n,&m))
    {
       
        for(i=1;i<=n;i++)
            scanf("%d",&a[i]);

        MakeTree(1,n,1);
        getchar();
        for(j=1;j<=m;j++)
        {
         scanf("%c%d%d",&c[0],&x,&y);
         getchar();
         if(c[0]=='U')
            UpdateTree(1,x,y);
         else
            cout<<QueryTree(x,y,1)<<endl;
       }
    }
    return 0;
}