#include<bits/stdc++.h>
using namespace std;
#define icc ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define int long long 
#define endl "\n"
#define PII pair<int,int>
const int N=1e6+5, INF=1e9+5, mod=1e9+7; 
int tree[N];
int n,m;
int a[N];
int lowbit(int x)
{
	return x&(-x);
}
void updata(int x,int val)
{
	//a[x]=val;
	while(x<=n)
	{
		tree[x]=val;
		for(int i=1;i<lowbit(x);i<<=1)
		{
			tree[x]=max(tree[x],tree[x-i]);
		}
		x+=lowbit(x);
	}
}
int query(int l,int r)
{
	int ans=0;
	while(l<=r)
	{
		ans=max(ans,a[r]);
		r--; 
		while(r-l>=lowbit(r))
		{
			ans=max(ans,tree[r]);
			r-=lowbit(r);
		}
	} return ans;
}
signed main()
{
	icc	
	while(cin>>n>>m)
	{
	
	for(int i=1;i<=n;i++) tree[i]=0;
	for(int i=1;i<=n;i++)
		cin>>a[i], updata(i,a[i]);
	while(m--)
	{
		char ch;
		int x,y;
		cin>>ch>>x>>y;
		if(ch=='U')
		{
			if(a[x]<y) updata(x,y),a[x]=y;
		}
		else
			cout<<query(x,y)<<endl;
	}
	}
}