1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 #define max(a, b) a>b?a:b 
 5 using namespace std;
 6 const int MAXN = 200020;
 7 struct Node
 8 {
 9     int max, left, right;    
10 } tree[MAXN * 3];
11 int n, m, num[MAXN];
12 int Build(int root, int left, int right)
13 {
14     int mid;
15     tree[root].left = left; 
16     tree[root].right = right;
17     if(left == right)  // 叶子； 
18         return tree[root].max = num[left];
19     mid = (left + right) / 2;
20     int a, b;
21     a = Build(2*root, left, mid);
22     b = Build(2*root + 1, mid + 1, right);
23     return tree[root].max = max(a, b);
24 } 
25 int Update(int root, int pos, int val)
26 {
27     if(pos < tree[root].left || tree[root].right < pos) //该点不在子段中 
28         return     tree[root].max;
29     if(pos == tree[root].left && pos == tree[root].right) //叶子； 
30         return tree[root].max = val;
31     int a, b;
32     a = Update(2*root, pos, val);    
33     b = Update(2*root+1, pos, val);
34     tree[root].max = max(a, b);
35     return tree[root].max;     
36 } 
37 int Find(int root, int left, int right)
38 {
39     int mid;
40     if(tree[root].left > right || tree[root].right < left) //没有相交线段； 
41         return 0;
42     if(tree[root].left >= left && tree[root].right <= right) // 有一段连续的线段包含在查找区间内； 
43         return tree[root].max;
44     int a, b;
45     a = Find(root*2, left, right);
46     b = Find(root*2 + 1, left, right);
47     return max(a, b);
48 } 
49 int main()
50 {
51     while(~scanf("%d %d", &n, &m))
52     {
53         for(int i = 1; i <= n; i++)
54             scanf("%d", &num[i]);
55         Build(1, 1, n); 
56         char str[10]; int a, b;
57         for(int i = 1; i <= m; i++)
58         {
59             cin >> str >> a >> b;
60             if(str[0] == ‘Q‘)
61                 printf("%d\n", Find(1, a, b));
62             else
63             {
64                 num[a] = b;
65                 Update(1, a, b); 
66             } 
67         }
68     }
69     return 0;
70 }