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hdu1754 I Hate It

#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
#define lson l,m,root<<1
#define rson m+1,r,root<<1|1
const int MAX = 250000;
int arr[MAX<<2];
int n;

void pushup(int root){
  arr[root] = max(arr[root<<1],arr[root<<1|1]);
}

void build(int l, int r, int root){
  if (l == r){
    scanf("%d",&arr[root]);
    return;
  }
  int m = (l+r)>>1;
  build(lson);
  build(rson);
  pushup(root);
}

void update(int id, int x, int l, int r, int root){
  if (l == r){
    arr[root] = x;
    return;
  }
  int m = (l+r)>>1;
  if (id<=m)
    update(id,x,lson);
  else
    update(id,x,rson);
  pushup(root);
}

int query(int x, int y, int l, int r, int root){
  if (x<=l && r<=y)
    return arr[root];
  int m = (l+r)>>1;
  int ans = 0;
  if (x<=m)ans = max(ans, query(x,y,lson));
  if (y>m)ans = max(ans, query(x,y,rson));
  return ans;
}

int main(){
//  freopen("in.txt","r",stdin);
  int i;
  int t;
  char ch;
  int a,b;
  while (scanf("%d %d",&n,&t)!=EOF){
    build(1, n, 1);
    for (i=0; i<t; i++){
      getchar();
      scanf("%c %d %d",&ch,&a,&b);
      if (ch == 'U')
        update(a,b,1,n,1);
      else
        printf("%d\n",query(a,b,1,n,1));
    }
  }
  return 0;
}