1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 using namespace std;
 5
 6 const int N=200000+50;
 7 struct tree{
 8     int l, r, maxn;
 9 };
10 tree t[N*3];
11 int ans;
12
13 void build(int m, int l, int r)
14 {
15     t[m].l = l;
16     t[m].r = r;
17     if(l==r)
18     {
19         scanf("%d", &t[m].maxn);
20         return;
21     }
22     int mid = (l + r) >> 1;
23     build(m<<1, l, mid);
24     build(m<<1|1, mid+1, r);
25     t[m].maxn = max(t[m<<1].maxn, t[m<<1|1].maxn);
26 }
27 void U(int m, int a, int b)
28 {
29     if(t[m].l == t[m].r && t[m].l == a)
30     {
31         t[m].maxn = b;
32         return;
33     }
34     int mid = (t[m].l + t[m].r) >> 1;
35     if(a <= mid)
36         U(m<<1, a, b);
37     else
38         U(m<<1|1, a, b);
39     t[m].maxn = max(t[m<<1].maxn, t[m<<1|1].maxn);
40 }
41 void Q(int m, int l, int r)
42 {
43     if(t[m].l == l && t[m].r == r)
44     {
45         ans = max(ans, t[m].maxn);
46         return;
47     }
48     int mid = (t[m].l + t[m].r) >> 1;
49     if(r <= mid)
50         Q(m<<1, l, r);
51     else if(l >= mid + 1)
52         Q(m<<1|1, l, r);
53     else
54     {
55         Q(m<<1, l, mid);
56         Q(m<<1|1, mid+1, r);
57     }
58 }
59 int main()
60 {
61     int n, m;
62     while(scanf("%d%d", &n, &m)!=EOF)
63     {
64         build(1, 1, n);
65         for(int i=0;i<m;i++)
66         {
67             getchar();
68             char c;
69             int a, b;
70             scanf("%c", &c);
71             scanf("%d%d", &a, &b);
72             if(c == 'Q')
73             {
74                 ans = 0;
75                 Q(1, a, b);
76                 printf("%d\n", ans);
77             }
78             else
79                 U(1, a, b);
80         }
81     }
82     return 0;
83 }