#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int N = 1e5 + 5;

struct Node{
    int arr[10], cnt;
}tree[N << 2];

void push_up(Node& node, Node l, Node r)
{
    int i = 1, j = 1, k = 1;
    while (i <= l.cnt && j <= r.cnt && k <= 8)
    {
        if (l.arr[i] >= r.arr[j]) node.arr[k++] = l.arr[i++];
        else node.arr[k++] = r.arr[j++];
    }
    while (i <= l.cnt && k <= 8) node.arr[k++] = l.arr[i++];
    while (j <= r.cnt && k <= 8) node.arr[k++] = r.arr[j++];
    node.cnt = k - 1;
}

void modify(int node, int lef, int rig, int x, int c)
{
    if (lef == rig) 
    {
        tree[node].arr[1] = c;
        tree[node].cnt = 1; 
    }
    else
    {
        int mid = (lef + rig) >> 1;
        int left_node = node << 1;
        int right_node = left_node | 1;
        if (x <= mid) modify(left_node, lef, mid, x, c);
        else modify(right_node, mid+1, rig, x, c);
        push_up(tree[node], tree[left_node], tree[right_node]);
    }
}

void bulid_tree(int node, int lef, int rig)
{
    if (lef == rig)
    {
        memset(tree[node].arr, 0, sizeof tree[node].arr);
        tree[node].cnt = 0; 
    } 
    else 
    {
        int mid = (lef + rig) >> 1;
        int left_node = node << 1;
        int right_node = node << 1 | 1;
        bulid_tree(left_node, lef, mid);
        bulid_tree(right_node, mid+1, rig);
    }
}

Node query(int node, int lef, int rig, int l, int r)
{
    if (l <= lef && rig <= r) return tree[node];
    int mid = (lef + rig) >> 1;
    int left_node = node << 1;
    int right_node = left_node | 1;

    Node res;
    memset(res.arr, 0, sizeof res.arr);
    res.cnt = 0;
    if (l <= mid) push_up(res, res, query(left_node, lef, mid, l, r));
    if (r > mid) push_up(res, res, query(right_node, mid+1, rig, l, r));
    return res;
}

int main()
{
    int n, m, x, y;
    char op[5];
    scanf("%d%d", &n, &m);
    bulid_tree(1, 1, n); //初始化 
    while (m--)
    {
        scanf("%s%d%d", op, &x, &y);
        if (op[0] == 'C') modify(1, 1, n, x, y);
        else 
        {
            if (y - x + 1 < 8) puts("0");
            else
            {
                Node res = query(1, 1, n, x, y);
                // for (int i = 1; i <= res.cnt; ++i) cout << res.arr[i] << " ";
                // cout << endl;
                printf("%d\n", res.arr[8]);
            }
        }
    }
    return 0;
}