#include <cstdio>
#include <cstring>
#include <cstdio>
#include <string>
#include <iostream>
#include <cmath>
 
using namespace std;
 
char com[100];
int a[200010];
int n;
 
struct Node{
    int l, r, v;
}tree[800050];
 
void Build(int pos, int l, int r){
    tree[pos].l = l;
    tree[pos].r = r;
    if(l == r){
        tree[pos].v = a[tree[pos].l];
        return ;
    }
    int mid = (l + r) / 2;
    Build(pos * 2, l, mid);
    Build(pos * 2 + 1, mid + 1, r);
    tree[pos].v = max(tree[pos * 2].v, tree[pos * 2 + 1].v);
}
 
void Update(int pos, int idx, int val){
    if(tree[pos].l == tree[pos].r){
        tree[pos].v = val;
        return ;
    }
    int mid = (tree[pos].l + tree[pos].r) / 2;
    if(idx <= mid)
        Update(pos * 2, idx, val);
    else
        Update(pos * 2 + 1, idx, val);
    tree[pos].v = max(tree[pos * 2].v, tree[pos * 2 + 1].v);
}
 
int Query(int pos, int l, int r){
    if(l <= tree[pos].l && tree[pos].r <= r){
        return tree[pos].v;
    }
    int ret = 0, mid = (tree[pos].l + tree[pos].r) / 2;
    if(l <= mid){
            ret =max(ret, Query(pos * 2, l, r));
    }
    if(r > mid){
            ret =max( ret, Query(pos * 2 + 1, l, r));
    }
    return ret;
}
 
int main(){
    int t, m;
    int x, y, i, j, k;
    int cnt = 0;
    while(~scanf("%d %d",&n ,&m)){
        cnt ++;
        for(i = 1; i <= n; i++){
            scanf("%d", &a[i]);
        }
        Build(1, 1, n);
        for(i = 0; i < m; i++){
            scanf ("%s", com);
            if(com[0] == 'Q'){
                //cout << com[0];
                scanf("%d%d", &x, &y);
                printf("%d\n", Query(1, x, y));
            }
            else if(com[0] == 'U'){
                //cout << com[0];
                scanf("%d%d", &x, &y);
                Update(1, x, y);
            }
        }
    }
    return 0;
}