5 6
1 2 3 4 5
Q 1 5
U 3 6
Q 3 4
Q 4 5
U 2 9
Q 1 5

5
6
5
9

Hint
Huge input,the C function scanf() will work better than cin
 

#include<iostream>
#include<cstdio>
#include<stdio.h>
#include<algorithm>
using namespace std;
const int MAX=200010; 
int nu[MAX];
struct data{
	int l,r,maxf;
}node[4*MAX];
void Build(int left,int right,int u){
	node[u].l=left;node[u].r=right;
	if(left==right){
		node[u].maxf=nu[left];
		return;
	}
	int mid=(left+right)/2;
	Build(left,mid,2*u);
	Build(mid+1,right,2*u+1);
	node[u].maxf=max(node[2*u].maxf,node[2*u+1].maxf);
}
//询问 
int query(int left,int right,int u){
	if((node[u].l>=left)&&(node[u].r<=right))
	  return node[u].maxf;
	int  mid=(node[u].l+node[u].r)/2;
	int ans=0;
	if(left<=mid) ans=max(ans,query(left,right,2*u));
	if(right>mid) ans=max(ans,query(left,right,2*u+1));
	return ans;
}
//更新 
int updata(int loc,int w,int u){
	if(node[u].l==node[u].r){
		node[u].maxf=w;
		return 0;
	}
	if(loc<=node[2*u].r){
		updata(loc,w,u*2);
	}
	else
	    updata(loc,w,u*2+1);
	node[u].maxf=max(node[2*u].maxf,node[2*u+1].maxf);
	return 0;
}

int main(){
	int n,m,i,a,b;
	char ch;
	while(~scanf("%d%d",&n,&m)){
		for(i=1;i<=n;++i)
		   scanf("%d",&nu[i]);
		Build(1,n,1);
		while(m--){
			cin>>ch>>a>>b;
			if(ch=='Q'){
				a=query(a,b,1);
				printf("%d\n",a);
			}
			else
			updata(a,b,1);
		}
		
	}
	return 0;
}