Seminar2

#include <algorithm>
#include <iostream>
#include <map>
#include <set>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <vector>

typedef long long ll;
using namespace std;

// 1 4 5 7 8
// 2 3 4 5 6 8 9 10 12 140

// 4 5 8

vector<int> Intersection(vector<int>& a, vector<int>& b) {
  vector<int> result;

  int i = 0, j = 0;
  while (i < a.size() && j < b.size()) {
    if (a[i] < b[j]) ++i;
    else if (a[i] > b[j]) ++j;
    else {
      result.push_back(a[i]);
      ++i; ++j;
    }
  }
  return result;
}

int main1() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int n = 0;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; ++i) cin >> a[i];
  int m = 0;
  cin >> m;
  vector<int> b(m);
  for (int i = 0; i < m; ++i) cin >> b[i];

  vector<int> result = Intersection(a, b);

  for (int x : result) cout << x << " ";

  return 0;
}

// 2 4 6 7 7 7 7 9 10 22 34
int main2() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int n = 0;
  cin >> n;
  int* b = new int[n];
  vector<int> a(n);
  for (int i = 0; i < n; ++i) { int v = 0; cin >> v; a[i] = v; b[i] = v; }
  int x = 0;
  cin >> x;

  auto position = lower_bound(a.begin(), a.end(), x, std::less<>());
  if (position != a.end() && *position == x) cout << "YES" << endl;
  else cout << "NO" << endl;

  auto position2 = lower_bound(b, b + n, x);
  if (position2 != b + n && *position2 == x) cout << "YES" << endl;
  else cout << "NO" << endl;

  delete[] b;
  return 0;
}

int main3() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int n = 0;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; ++i) cin >> a[i];

  // 2 4 3 2 1
  int l = 1, r = n;
  while (l < r) {
    int mid = (r + l) / 2;
    if (a[mid] > a[mid - 1]) l = mid + 1;
    else r = mid;
  }
  cout << l - 1;

  return 0;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int n = 0;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; ++i) cin >> a[i];
  int m = 0;
  cin >> m;

  // 2 4 3 2 1
  int l = 0, r = m;
  ll sum = 0;
  for (int i = l; i < r; ++i) sum += a[i];

  ll max_sum = sum;
  for (; r < n; ++l, ++r) {
    sum += a[r];
    sum -= a[l];
    max_sum = max(sum, max_sum);
  }
  cout << max_sum;
  return 0;
}