1 /*
2 线段树基本功能：区间最大值，修改某个值
3 */
4 #include <cstdio>
5 #include <cstring>
6 #include <algorithm>
7 #define lson l, m, rt << 1
8 #define rson m+1, r, rt << 1|1
9
10 const int MAX_N = 200000 + 10;
11 int sum[MAX_N<<2];
12 int a[MAX_N<<2];
13
14 void pushup(int rt)
15 {
16 sum[rt] = sum[rt<<1] + sum[rt<<1|1];
17 }
18
19 void maxrt(int rt)
20 {
21 sum[rt] = std::max (sum[rt<<1], sum[rt<<1|1]);
22 }
23
24 void build(int l, int r, int rt)
25 {
26 if (l == r)
27 {
28 scanf ("%d", &sum[rt]);
29 return ;
30 }
31 int m = (l + r) >> 1;
32 build (lson);
33 build (rson);
34 maxrt (rt);
35 }
36
37 void update(int p, int up, int l, int r, int rt)
38 {
39 if (l == r)
40 {
41 sum[rt] = up;
42 return ;
43 }
44 int m = (l + r) >> 1;
45 if (p <= m) update (p, up, lson);
46 else update (p, up, rson);
47 maxrt (rt);
48 }
49
50 int query(int ql, int qr, int l, int r, int rt)
51 {
52 if (ql <= l && r <= qr)
53 {
54 return sum[rt];
55 }
56 int m = (l + r) >> 1;
57 int ans = 0;
58 if (ql <= m) ans = std::max(ans, query (ql, qr, lson));
59 if (qr > m) ans = std::max(ans, query (ql, qr, rson));
60
61 return ans;
62 }
63
64
65 int main(void) //HDU 1754 I Hate It
66 {
67 //freopen ("inB.txt", "r", stdin);
68 int n, m, ans, b, c;
69 char ch[2];
70
71 while (~scanf ("%d%d", &n, &m))
72 {
73 build (1, n, 1);
74 while (m--)
75 {
76 scanf ("%s%d%d", &ch, &b, &c);
77 if (ch[0] == 'Q')
78 {
79 ans = query (b, c, 1, n, 1);
80 printf ("%d
", ans);
81 }
82 if (ch[0] == 'U')
83 {
84 update (b, c, 1, n, 1);
85 }
86 }
87 }
88
89 return 0;
90 }