mycpptemplate.cpp

#include <bits/stdc++.h>
using namespace std;
#define int long long int
#define pb push_back
#define pll pair<int, int>
const int modll = 1e17;
const int mod = 1e9 + 7;
const int INF = 1e18;
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};
vector<int> seive(int n) { vector<int> prime(n+1, 1); for(int i=2; i*i<=n; i++) if(prime[i]) for(int j=i*i; j<=n; j+=i) prime[j]=0; return prime; }
template <typename T> void takeInput(vector<T> &a, int n) { for(int i=0; i<n; i++) { T ele; cin>>ele; a[i]=ele; } }
template <typename T> void printArr(vector<T> &a) { for(auto it:a) cout<<it<<" "; cout<<endl; }
int fastPow(int a, int b) { int res=1; while(b) { if(b&1) res=(res*a)%mod; a=(a*a)%mod; b>>=1; } return res; }
int gcd(int a, int b) { return b==0 ? a : gcd(b, a%b); }
int lcm(int a, int b) { return (a/gcd(a,b))*b; }
int modInverse(int a) { return fastPow(a, mod-2); }
int modAdd(int a, int b) { return (a + b) % mod; }
int modSub(int a, int b) { return (a - b + mod) % mod; }
int modMul(int a, int b) { return (1LL * a * b) % mod; }
vector<int> factorial, inverseFactorial;
void precomputeCombi(int n) { factorial.resize(n+1); inverseFactorial.resize(n+1); factorial[0]=1; for(int i=1;i<=n;i++) factorial[i]=modMul(factorial[i-1],i); inverseFactorial[n]=fastPow(factorial[n],mod-2); for(int i=n-1;i>=0;i--) inverseFactorial[i]=modMul(inverseFactorial[i+1],i+1); }
int NCR(int n, int r) { if(r<0||r>n) return 0; return modMul(factorial[n],modMul(inverseFactorial[r],inverseFactorial[n-r])); }
int _;
vector<int> __;
vector<vector<int>> __2d;
// Segtree: 
vector<int>nums,segTree;
// time Complexity => O(n);
// space complexity => O(2*n);
void build(int i, int l, int r) {
    if (l == r) {
        segTree[i] = nums[l];
        return;
    }
    int mid = (l + r) / 2;
    build(2*i+1, l, mid);
    build(2*i+2, mid+1, r);
    segTree[i] = segTree[2*i+1] + segTree[2*i+2];
}

void update(int i, int l, int r, int idx, int val) {
    if (l == r) {
        nums[idx] = val;
        segTree[i] = val;
        return;
    }
    int mid = (l + r) / 2;
    if (idx <= mid) {
        update(2*i+1, l, mid, idx, val);
    } else {
        update(2*i+2, mid+1, r, idx, val);
    }
    segTree[i] = segTree[2*i+1] + segTree[2*i+2];
}

int query(int i, int l, int r, int start, int end) {
    if (l > end || r < start) return 0;
    if (l >= start && r <= end) return segTree[i];
    int mid = (l + r) / 2;
    return query(2*i+1, l, mid, start, end) +
           query(2*i+2, mid+1, r, start, end);
}   

void solve() {
    int n = 8;
    segTree.resize(4 * n);
    nums.resize(n, 1);
    build(0, 0, n-1);
    update(0, 0, n-1, 2, 2000);
    int ans = query(0, 0, n-1, 2, 4);
    cout << ans << endl;
}

bool multi = false;
int32_t main(){
   ios_base::sync_with_stdio(false);
   cin.tie(NULL);
   cout.tie(NULL);
   auto start = chrono::high_resolution_clock::now();
   int t = 1;
   if(multi) cin >> t;
   while(t--){
       solve();
   }
   auto end = chrono::high_resolution_clock::now();
   auto elapsed = chrono::duration_cast<chrono::nanoseconds>(end - start);
   cerr << fixed << setprecision(10) << "Time measured: " << static_cast<double>(elapsed.count()) * 1e-9 << " seconds.\n";
   return 0;
}