#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#define ll long long
#define ls p<<1
#define rs p<<1|1 
using namespace std;
const int MN=2e5+5;
char opt;
ll n,m,l,r,a[MN];
struct node{ll l,r,num;}t[MN<<2];
void write(ll n){if(n<0){putchar('-');write(-n);return;}if(n>9)write(n/10);putchar(n%10+'0');}
ll read(){ll x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+(ch^48);ch=getchar();}return x*f;}
void build(ll p, ll l, ll r){
	t[p].l=l,t[p].r=r;
	if(l==r){t[p].num=a[l];return;}
	ll mid=(l+r)>>1;
	build(ls,l,mid);build(rs,mid+1,r);
	t[p].num=max(t[p].num,max(t[ls].num,t[rs].num));
}
void change(ll p, ll l, ll r, ll v){
	if(l<=t[p].l&&t[p].r<=r){t[p].num=max(t[p].num,v);return;}
	ll mid=(t[p].l+t[p].r)>>1;
	if(l<=mid) change(ls,l,r,v);
	if(r>mid) change(rs,l,r,v);
	t[p].num=max(t[p].num,max(t[ls].num,t[rs].num));
}
ll query(ll p, ll l, ll r){
	if(l<=t[p].l&&t[p].r<=r) return t[p].num;
	ll mid=(t[p].l+t[p].r)>>1,res=0;
	if(l<=mid) res=max(res,query(ls,l,r));
	if(r>mid) res=max(res,query(rs,l,r));
	return res;
}
int main(){
	n=read();m=read();for(int i=1; i<=n; i++) a[i]=read();build(1,1,n);while(m--){
		opt=getchar();l=read();r=read();
		if(opt=='Q') write(query(1,l,r)),putchar('\n');
		else change(1,l,l,r);
	}
	return 0;
}

rt，我下载了我错误的测试数据点，比较了一下，一模一样，错误信息是第一行输出过短……