#include <bits/stdc++.h>
using namespace std;
const int maxn = 200000+500;
struct node
{
int l,r;
int maxx;
}tree[4*maxn];
int a[maxn];
void push_up(int i)
{
tree[i].maxx = max(tree[i<<1].maxx,tree[i<<1|1].maxx);
}
void build(int i,int l,int r)
{
tree[i].l = l,tree[i].r = r;
tree[i].maxx = 0;
if(l==r)
{
tree[i].maxx = a[r];
return ;
}
int mid = (l+r)>>1;
build(i<<1,l,mid);
build(i<<1|1,mid+1,r);
push_up(i);
}
void update(int i,int pos,int val)
{
int l = tree[i].l;
int r = tree[i].r;
if(l==r && l==pos)
{
tree[i].maxx = val;
return ;
}
int mid = (l+r)>>1;
if(mid>=pos)
update(i<<1,pos,val);
else
update(i<<1|1,pos,val);
push_up(i);
}
int query(int i,int l,int r)
{
int L = tree[i].l;
int R = tree[i].r;
if(l<=L && R<=r)
return tree[i].maxx;
int mid = (L+R)>>1;
int ans = 0;
if(mid<r)
ans = query(i<<1|1,l,r);
if(mid>=l)
ans = max(ans,query(i<<1,l,r));
return ans;
}
int main(void)
{
int n,m;
while(~scanf("%d %d",&n,&m))
{
for(int i=1;i<=n;i++)
scanf("%d",&a[i]);
build(1,1,n);
while(m--)
{
char op[10];
int x,y;
scanf("%s %d %d",op,&x,&y);
if(op[0]=='U')
update(1,x,y);
else
printf("%d\n",query(1,x,y));
}
}
return 0;
}
