#include<iostream>
using namespace std;
int n,m,a[220000];
int tree[810000],lazyA[410000];
void build(int l,int r,int id)
{
	if(l==r) tree[id]=a[l];
	else
	{
		int mid=(l+r)/2;
		build(l,mid,id*2);
		build(mid+1,r,id*2+1);
		tree[id]=max(tree[id*2],tree[id*2+1]);
	}	
}
int ask(int l,int r,int id,int x,int y)
{
	if(r<x||l>y) return 0;
	if(l<x||y<r)
	{
		int mid=(l+r)/2;
		return max(ask(l,mid,id*2,x,y),ask(mid+1,r,id*2+1,x,y));
	}
	return tree[id];
}
void change(int l,int r,int id,int x1,int x2)
{
	if(l==r) tree[id]=x2;
	else
	{
		int mid=(l+r)/2;
		if(mid<x1) change(mid+1,r,id*2+1,x1,x2);
		else if(mid>=x1) change(l,mid,id*2,x1,x2);
		tree[id]=max(tree[id*2],tree[id*2+1]);
	}
}
int main()
{
	cin>>n>>m;
	for(int i=1;i<=n;i++)
	cin>>a[i];
	build(1,n,1);
	for(int i=1;i<=m;i++)
	{
		char c;
		cin>>c;
		if(c=='Q')
		{
			int t1,t2;
			cin>>t1>>t2;
			cout<<ask(1,n,1,t1,t2)<<endl;
		}
		else if(c=='U')
		{
			int t1,t2;
			cin>>t1>>t2;
			if(a[t1]<t2) change(1,n,1,t1,t2);
		}
		
	}
	return 0;
}