#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
struct dynamic_segment_tree {
using T = i64;
static T ide() { return 0ll; }
static T ope(const T& a, const T& b) { return a + b; }
struct node {
node* left;
node* right;
T val;
node(T v): val(v), left(nullptr), right(nullptr) {}
};
i64 n;
node* root;
dynamic_segment_tree(const i64 sz): root(new node(ide())) {
n = 1;
while(n < sz) n *= 2;
}
T value(node* n) {
if(n) return n->val;
else return ide();
}
void update(node* n, i64 i, T x, i64 l, i64 r) {
if(l + 1 == r) {
n->val = x;
}
else {
i64 m = (l + r) / 2;
if(i < m) {
if(!n->left) {
n->left = new node(ide());
}
update(n->left, i, x, l, m);
}
else {
if(!n->right) {
n->right = new node(ide());
}
update(n->right, i, x, m, r);
}
n->val = ope(value(n->left), value(n->right));
}
}
T get(node* n, i64 a, i64 b, i64 l, i64 r) {
if(!n) return ide();
if(a <= l && r <= b) return value(n);
else if(r <= a || b <= l) return ide();
else return ope(get(n->left, a, b, l, (l + r) / 2), get(n->right, a, b, (l + r) / 2, r));
}
void update(i64 i, T x) {
update(root, i, x, 0, n);
}
T sum(i64 a, i64 b) {
return get(root, a, b, 0, n);
}
};