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int h; // = __lg(2*n)
//a value that is not used by the update query:
constexpr ll updateFlag = -1;
vector<ll> d(N, updateFlag);
void apply(int p, ll value, int k) {
tree[p] = value * k;
if (p < sz(tree)/2) d[p] = value;
}
void build(int p) {
p >>= __builtin_ctzll(p);
for (int k = 2; p > 1; k <<= 1) {
p/=2;
if (d[p] == updateFlag) tree[p] = tree[2*p] + tree[2*p+1];
else tree[p] = d[p] * k;
}}
void push(int p) {
for (int s = h, k = 1 << (h-1); s > 0; s--, k/=2) {
int i = p >> s;
if (d[i] != updateFlag) {
apply(2*i , d[i], k);
apply(2*i+1, d[i], k);
d[i] = updateFlag;
}}}
void update(int l, int r, ll value) { // assign value
if (value == updateFlag) return;
l += sz(tree)/2, r += sz(tree)/2;
push(l);
push(r - 1);
int l0 = l, r0 = r, k = 1;
for (; l < r; l /= 2, r /= 2, k *= 2) {
if (l&1) apply(l++, value, k);
if (r&1) apply(--r, value, k);
}
build(l0);
build(r0 - 1);
}
ll query(int l, int r) { // sum(l..r)
l += sz(tree)/2, r += sz(tree)/2;
push(l);
push(r - 1);
ll res = query_default;
for (; l < r; l /= 2, r /= 2) {
if (l&1) res = res + tree[l++];
if (r&1) res = tree[--r] + res;
}
return res;
}
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