#include <cstdio>
#include <cstring>
#include <algorithm>
#include <map>
#include <queue>
#include <cctype>
#define MP(a, b) make_pair(a, b)
using namespace std;
const int MAXN = 2e5 + 5;
const int INF = 0x3f3f3f3f;
 
struct SEG
{
    int l, r, vmax;
}segt[MAXN << 2];
 
inline int ReadInt()
{
    static int r, sign;
    static char ch;
    r = 0, sign = 1;
    while ((ch = getchar()) && !isdigit(ch));
    if (ch == '-')
        sign = -1, ch = getchar();
    while (isdigit(ch))
        r = r * 10 + ch - '0', ch = getchar();
    return sign * r;
}
 
void PushUp(int cur)
{
    segt[cur].vmax = max(segt[cur << 1].vmax, segt[cur << 1 | 1].vmax);
}
 
void Build(int cur, int l, int r)
{
    segt[cur].l = l, segt[cur].r = r;
    if (l == r)
    {
        segt[cur].vmax = ReadInt();
        return;
    }
    int mid = l + ((r - l) >> 1);
    Build(cur << 1, l, mid);
    Build(cur << 1 | 1, mid + 1, r);
    PushUp(cur);
}
 
int Query(int cur, int l, int r)
{
    int ans = -1, x = -1, y = -1;
    int mid = segt[cur].l + ((segt[cur].r - segt[cur].l) >> 1);
    if (segt[cur].l == l && segt[cur].r == r)
        return segt[cur].vmax;
    if (r <= mid)
        ans = max(Query(cur << 1, l, r), ans);
    else if (l > mid)
        ans = max(ans, Query(cur << 1 | 1, l, r));
    else
    {
        x = Query(cur << 1, l, mid);
        y = Query(cur << 1 | 1, mid + 1, r);
    }
    return max(ans, max(x, y));
}
 
void Update(int cur, int pos, int val)
{
    int mid = segt[cur].l + ((segt[cur].r - segt[cur].l) >> 1);
    if (segt[cur].l == pos && segt[cur].r == pos)
    {
        segt[cur].vmax = val;
        return;
    }
    if (pos <= mid)
        Update(cur << 1, pos, val);
    else
        Update(cur << 1 | 1, pos, val);
    PushUp(cur);
}
 
int main()
{
    //freopen("input.txt", "r", stdin);
    int nstu, nq, i, j;
    while (~scanf("%d%d", &nstu, &nq))
    {
        Build(1, 1, nstu);
        while (nq--)
        {
            int a, b;
            char str[10];
            scanf("%s%d%d", str, &a, &b);
            if (str[0] == 'Q')
                printf("%d\n", Query(1, a, b));
            else
                Update(1, a, b);
        }
        
    }
    return 0;
}