#include<stdio.h>
#include<string.h>
#include<math.h>
#include<algorithm>
#define N 200010
#define Lson root<<1, L, tree[root].Mid()
#define Rson root<<1|1, tree[root].Mid() + 1, R

using namespace std;

struct Tree
{
    int L, R, Max;
    int Mid()
    {
        return (L + R) / 2;
    }
}tree[N * 4];

int al[N];

void Build(int root, int L, int R)
{
    tree[root].L = L, tree[root].R = R;
    if(L == R)
    {
        tree[root].Max = al[L];
        return ;
    }

    Build(Lson);
    Build(Rson);

    tree[root].Max = max(tree[root<<1].Max, tree[root<<1|1].Max);
}

void Update(int root, int k, int e)
{
    if(tree[root].L == tree[root].R)
    {
        tree[root].Max = e;
        return ;
    }
    if(k <= tree[root].Mid())
        Update(root<<1, k, e);
    else
        Update(root<<1|1, k, e);
    tree[root].Max = max(tree[root<<1].Max, tree[root<<1|1].Max);//更新k点后，还要更新节点的最大值，上一区间节点的最大值取下面左右两个区间节点的最大值
}

int Query(int root, int L, int R)
{
    if(tree[root].L == L && tree[root].R == R)
        return tree[root].Max;
    if(R <= tree[root].Mid())
        return Query(root<<1, L, R);
    else if(L > tree[root].Mid())
        return Query(root<<1|1, L, R);
    else
        return max(Query(Lson), Query(Rson));
}

int main()
{
    int n, m, a, b, i;
    char s[10];
    while(~scanf("%d%d", &n, &m))
    {
        for(i = 1 ; i <= n ; i++)
            scanf("%d", &al[i]);
            Build(1, 1, n);
            while(m--)
            {
                scanf("%s%d%d", s, &a, &b);
                if(s[0] == ‘U‘)
                    Update(1, a, b);
                else
                    printf("%d\n", Query(1, a, b));
            }
    }
    return 0;
}
/*
10 2
1 2 3 4 5 10 6 7 8 9
U 6 8
Q 1 6
*/