#include <bits/stdc++.h>
using namespace std;
const long long llmax = 9223372036854775807;
const long long llmin = -9223372036854775808;
const int intmin = -2147483648;
const int intmax = 2147483647;
const int mod = 1e9 + 7;
long long gcd(long long a, long long b) {
  if (a == 0 || b == 0)
    return a + b;
  else
    return gcd(b, a % b);
}
template <typename A, typename B>
inline A fexp(A x, B p) {
  A ans = 1;
  for (; p; p >>= 1, x = 1LL * x * x % mod)
    if (p & 1) ans = 1LL * ans * x % mod;
  return ans;
}
template <typename T>
inline void read(T& x) {
  x = 0;
  T f = 1;
  char ch;
  do {
    ch = getchar();
    if (ch == '-') f = -1;
  } while (ch < '0' || ch > '9');
  do x = x * 10 + ch - '0', ch = getchar();
  while (ch <= '9' && ch >= '0');
  x *= f;
}
vector<long long> primes;
template <class T>
bool isPrime(T x) {
  if (x <= 4 || x % 2 == 0 || x % 3 == 0) return x == 2 || x == 3;
  for (T i = 5; i * i <= x; i += 6)
    if (x % i == 0 || x % (i + 2) == 0) return 0;
  return 1;
}
int Tcnt = 0;
int dv[1000001];
template <class TT>
class ST {
  struct Node {
    int l, r;
    long long sm, bjc, bjj;
    long long min;
    long long max;
    long long oor;
    long long andd;
    vector<int> cnt;
  };
  vector<TT> A;
  vector<Node> T;

 public:
  ST(vector<TT>& AA) {
    A.emplace_back(0);
    for (int i = 0; i < AA.size(); i++) A.emplace_back(AA[i]);
    T.resize(A.size() << 2);
    build(1, 1, (int)A.size() - 1);
  }
  long long QuerySum(int l, int r) { return querySum(1, l, r); }
  void QueryCnt(int l, int r, vector<int>& cnt) {
    return queryCount(1, l, r, cnt);
  }
  long long QueryOr(int l, int r) { return queryOr(1, l, r); }
  long long QueryAnd(int l, int r) { return queryAnd(1, l, r); }
  long long QueryMax(int l, int r) { return queryMax(1, l, r); }
  long long QueryMin(int l, int r) { return queryMin(1, l, r); }
  void Add(int l, int r, TT x) { add(1, l, r, x); }
  void Mul(int l, int r, TT x) { mul(1, l, r, x); }

 private:
  void pushup(int i) {
    T[i].sm = T[i << 1].sm + T[i << 1 | 1].sm;
    T[i].max = max(T[i << 1].max, T[i << 1 | 1].max);
    T[i].min = min(T[i << 1].min, T[i << 1 | 1].min);
    T[i].oor = (T[i << 1].oor) | (T[i << 1 | 1].oor);
    T[i].andd = (T[i << 1].andd) & (T[i << 1 | 1].andd);
    for (int j = (1); j <= (40); j++)
      T[i].cnt[j - 1] = T[i << 1].cnt[j - 1] + T[i << 1 | 1].cnt[j - 1];
  }
  void mul(int i, TT x) {
    T[i].sm *= x;
    T[i].bjc *= x;
    T[i].bjj *= x;
  }
  void add(int i, TT x) {
    T[i].sm += x * (T[i].r - T[i].l + 1);
    T[i].max += x;
    T[i].min -= x;
    T[i].bjj += x;
    if (x == 0) return;
    if (x == 1) {
      for (int j = (1); j <= (40); j++)
        T[i].cnt[40 - (j - 1)] = T[i].cnt[40 - (j - 1) - 1];
      T[i].cnt[0] = 0;
    } else {
      int idx;
      for (idx = 0; idx < 40; idx++) {
        if (T[i].cnt[idx]) {
          T[i].cnt[idx] = 0;
          break;
        }
      }
      idx += x;
      if (idx >= 0 && idx < 40) T[i].cnt[idx] = 1;
    }
  }
  void pushdown(int i) {
    add(i << 1, T[i].bjj);
    add(i << 1 | 1, T[i].bjj);
    T[i].bjj = 0;
  }
  void build(int i, int l, int r) {
    T[i].l = l;
    T[i].r = r;
    T[i].bjc = 1, T[i].cnt.resize(40);
    if (l == r) {
      T[i].sm = A[l];
      T[i].min = A[l];
      T[i].max = A[l];
      T[i].oor = A[l];
      T[i].andd = A[l];
      if (A[l] < 40) T[i].cnt[A[l]] = 1;
      return;
    }
    int M = l + r >> 1;
    build(i << 1, l, M);
    build(i << 1 | 1, M + 1, r);
    pushup(i);
  }
  long long querySum(int i, int l, int r) {
    if (l <= T[i].l && T[i].r <= r) return T[i].sm;
    int M = T[i].l + T[i].r >> 1;
    long long ans = 0;
    pushdown(i);
    if (l <= M) ans += querySum(i << 1, l, r);
    if (r > M) ans += querySum(i << 1 | 1, l, r);
    return ans;
  }
  void queryCount(int i, int l, int r, vector<int>& cnt) {
    if (l <= T[i].l && T[i].r <= r) {
      for (int j = (1); j <= (40); j++) cnt[j - 1] += T[i].cnt[j - 1];
      return;
    }
    int M = T[i].l + T[i].r >> 1;
    pushdown(i);
    if (l <= M) queryCount(i << 1, l, r, cnt);
    if (r > M) queryCount(i << 1 | 1, l, r, cnt);
    return;
  }
  long long queryOr(int i, int l, int r) {
    if (l <= T[i].l && T[i].r <= r) return T[i].oor;
    int M = T[i].l + T[i].r >> 1;
    long long ans = 0;
    pushdown(i);
    if (l <= M) ans = queryOr(i << 1, l, r);
    if (r > M) ans |= queryOr(i << 1 | 1, l, r);
    return ans;
  }
  long long queryAnd(int i, int l, int r) {
    if (l <= T[i].l && T[i].r <= r) return T[i].andd;
    int M = T[i].l + T[i].r >> 1;
    long long ans = 0;
    pushdown(i);
    bool set = false;
    if (l <= M) ans = queryAnd(i << 1, l, r), set = true;
    if (r > M)
      ans =
          set ? (ans & queryAnd(i << 1 | 1, l, r)) : queryAnd(i << 1 | 1, l, r);
    return ans;
  }
  long long queryMax(int i, int l, int r) {
    if (l <= T[i].l && T[i].r <= r) return T[i].max;
    int M = T[i].l + T[i].r >> 1;
    long long ans = llmin;
    pushdown(i);
    if (l <= M) ans = max(ans, queryMax(i << 1, l, r));
    if (r > M) ans = max(ans, queryMax(i << 1 | 1, l, r));
    return ans;
  }
  long long queryMin(int i, int l, int r) {
    if (l <= T[i].l && T[i].r <= r) return T[i].min;
    int M = T[i].l + T[i].r >> 1;
    long long ans = llmax;
    pushdown(i);
    if (l <= M) ans = min(ans, queryMin(i << 1, l, r));
    if (r > M) ans = min(ans, queryMin(i << 1 | 1, l, r));
    return ans;
  }
  void addnew(int i, TT x) {
    T[i].sm = dv[T[i].sm];
    T[i].bjj = 0;
    T[i].max = T[i].sm;
    T[i].min = T[i].sm;
    return;
  }
  void add(int i, int l, int r, TT x) {
    if (l <= T[i].l && T[i].r <= r) {
      add(i, x);
      return;
    }
    int M = T[i].l + T[i].r >> 1;
    pushdown(i);
    if (l <= M) add(i << 1, l, r, x);
    if (r > M) add(i << 1 | 1, l, r, x);
    pushup(i);
  }
  void mul(int i, int l, int r, TT x) {
    if (l <= T[i].l && T[i].r <= r) {
      mul(i, x);
      return;
    }
    int M = T[i].l + T[i].r >> 1;
    pushdown(i);
    if (l <= M) mul(i << 1, l, r, x);
    if (r > M) mul(i << 1 | 1, l, r, x);
    pushup(i);
  }
};
struct less_than_key {
  inline bool operator()(const string& struct1, const string& struct2) {
    return (struct1.size() > struct2.size());
  }
};
long long func(long long n, long long m, long long r, long long x,
               long long y) {
  long long val =
      (min(n + 1, x + r) - max(x, r)) * (min(m + 1, y + r) - max(y, r));
  return val;
}
class triplet {
 public:
  long long x, y, val;
  triplet(long long _x, long long _y, long long _val)
      : x(_x), y(_y), val(_val){};
  inline bool operator<(const triplet& other) const { return val < other.val; }
};
bool sortbysec(const pair<int, int>& a, const pair<int, int>& b) {
  return (a.second < b.second);
}
const long long MAX_VALUE = 1LL * 1000 * 1000 * 1000 * 1000 * 1000 * 1000;
int ans = 0;
int n, m;
vector<int> edges[100001];
vector<int> ar;
bool DFS(int vtx, int cons, int par) {
  if (edges[vtx].size() == 1 && vtx != 1) {
    ans++;
    return true;
  }
  for (auto& ch : edges[vtx]) {
    if (ar[ch] + cons <= m && ch != par) {
      if (ar[ch] == 1)
        DFS(ch, ar[ch] + cons, vtx);
      else
        DFS(ch, 0, vtx);
    }
  }
  return true;
}
bool isPrime(long long x) {
  if (x <= 4 || x % 2 == 0 || x % 3 == 0) return x == 2 || x == 3;
  for (long long i = 5; i * i <= x; i += 6)
    if (x % i == 0 || x % (i + 2) == 0) return 0;
  return 1;
}
long long fac[41];
long long bill = 1000000000;
long long dp[101][101];
int b[100001];
int main() {
  std::cin.sync_with_stdio(false);
  std::cin.tie(nullptr);
  bool test = false;
  if (test) freopen("/Users/aj/code/HackerRank/input.txt", "r", stdin);
  int n;
  cin >> n;
  set<int> st;
  int mx = 0;
  for (int i = (1); i <= (2 * n); i++) {
    int v;
    cin >> v;
    if (st.find(v) == st.end())
      st.emplace(v);
    else
      st.erase(v);
    if (st.size() > mx) mx = st.size();
  }
  cout << mx;
}

### Prompt

Your challenge is to write a Cpp solution to the following problem:

Andryusha is an orderly boy and likes to keep things in their place.

Today he faced a problem to put his socks in the wardrobe. He has n distinct pairs of socks which are initially in a bag. The pairs are numbered from 1 to n. Andryusha wants to put paired socks together and put them in the wardrobe. He takes the socks one by one from the bag, and for each sock he looks whether the pair of this sock has been already took out of the bag, or not. If not (that means the pair of this sock is still in the bag), he puts the current socks on the table in front of him. Otherwise, he puts both socks from the pair to the wardrobe.

Andryusha remembers the order in which he took the socks from the bag. Can you tell him what is the maximum number of socks that were on the table at the same time? 

Input

The first line contains the single integer n (1 ≤ n ≤ 105) — the number of sock pairs.

The second line contains 2n integers x1, x2, ..., x2n (1 ≤ xi ≤ n), which describe the order in which Andryusha took the socks from the bag. More precisely, xi means that the i-th sock Andryusha took out was from pair xi.

It is guaranteed that Andryusha took exactly two socks of each pair.

Output

Print single integer — the maximum number of socks that were on the table at the same time.

Examples

Input

1
1 1


Output

1


Input

3
2 1 1 3 2 3


Output

2

Note

In the first example Andryusha took a sock from the first pair and put it on the table. Then he took the next sock which is from the first pair as well, so he immediately puts both socks to the wardrobe. Thus, at most one sock was on the table at the same time.

In the second example Andryusha behaved as follows: 

  * Initially the table was empty, he took out a sock from pair 2 and put it on the table. 
  * Sock (2) was on the table. Andryusha took out a sock from pair 1 and put it on the table. 
  * Socks (1, 2) were on the table. Andryusha took out a sock from pair 1, and put this pair into the wardrobe. 
  * Sock (2) was on the table. Andryusha took out a sock from pair 3 and put it on the table. 
  * Socks (2, 3) were on the table. Andryusha took out a sock from pair 2, and put this pair into the wardrobe. 
  * Sock (3) was on the table. Andryusha took out a sock from pair 3 and put this pair into the wardrobe. 

Thus, at most two socks were on the table at the same time.

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
const long long llmax = 9223372036854775807;
const long long llmin = -9223372036854775808;
const int intmin = -2147483648;
const int intmax = 2147483647;
const int mod = 1e9 + 7;
long long gcd(long long a, long long b) {
  if (a == 0 || b == 0)
    return a + b;
  else
    return gcd(b, a % b);
}
template <typename A, typename B>
inline A fexp(A x, B p) {
  A ans = 1;
  for (; p; p >>= 1, x = 1LL * x * x % mod)
    if (p & 1) ans = 1LL * ans * x % mod;
  return ans;
}
template <typename T>
inline void read(T& x) {
  x = 0;
  T f = 1;
  char ch;
  do {
    ch = getchar();
    if (ch == '-') f = -1;
  } while (ch < '0' || ch > '9');
  do x = x * 10 + ch - '0', ch = getchar();
  while (ch <= '9' && ch >= '0');
  x *= f;
}
vector<long long> primes;
template <class T>
bool isPrime(T x) {
  if (x <= 4 || x % 2 == 0 || x % 3 == 0) return x == 2 || x == 3;
  for (T i = 5; i * i <= x; i += 6)
    if (x % i == 0 || x % (i + 2) == 0) return 0;
  return 1;
}
int Tcnt = 0;
int dv[1000001];
template <class TT>
class ST {
  struct Node {
    int l, r;
    long long sm, bjc, bjj;
    long long min;
    long long max;
    long long oor;
    long long andd;
    vector<int> cnt;
  };
  vector<TT> A;
  vector<Node> T;

 public:
  ST(vector<TT>& AA) {
    A.emplace_back(0);
    for (int i = 0; i < AA.size(); i++) A.emplace_back(AA[i]);
    T.resize(A.size() << 2);
    build(1, 1, (int)A.size() - 1);
  }
  long long QuerySum(int l, int r) { return querySum(1, l, r); }
  void QueryCnt(int l, int r, vector<int>& cnt) {
    return queryCount(1, l, r, cnt);
  }
  long long QueryOr(int l, int r) { return queryOr(1, l, r); }
  long long QueryAnd(int l, int r) { return queryAnd(1, l, r); }
  long long QueryMax(int l, int r) { return queryMax(1, l, r); }
  long long QueryMin(int l, int r) { return queryMin(1, l, r); }
  void Add(int l, int r, TT x) { add(1, l, r, x); }
  void Mul(int l, int r, TT x) { mul(1, l, r, x); }

 private:
  void pushup(int i) {
    T[i].sm = T[i << 1].sm + T[i << 1 | 1].sm;
    T[i].max = max(T[i << 1].max, T[i << 1 | 1].max);
    T[i].min = min(T[i << 1].min, T[i << 1 | 1].min);
    T[i].oor = (T[i << 1].oor) | (T[i << 1 | 1].oor);
    T[i].andd = (T[i << 1].andd) & (T[i << 1 | 1].andd);
    for (int j = (1); j <= (40); j++)
      T[i].cnt[j - 1] = T[i << 1].cnt[j - 1] + T[i << 1 | 1].cnt[j - 1];
  }
  void mul(int i, TT x) {
    T[i].sm *= x;
    T[i].bjc *= x;
    T[i].bjj *= x;
  }
  void add(int i, TT x) {
    T[i].sm += x * (T[i].r - T[i].l + 1);
    T[i].max += x;
    T[i].min -= x;
    T[i].bjj += x;
    if (x == 0) return;
    if (x == 1) {
      for (int j = (1); j <= (40); j++)
        T[i].cnt[40 - (j - 1)] = T[i].cnt[40 - (j - 1) - 1];
      T[i].cnt[0] = 0;
    } else {
      int idx;
      for (idx = 0; idx < 40; idx++) {
        if (T[i].cnt[idx]) {
          T[i].cnt[idx] = 0;
          break;
        }
      }
      idx += x;
      if (idx >= 0 && idx < 40) T[i].cnt[idx] = 1;
    }
  }
  void pushdown(int i) {
    add(i << 1, T[i].bjj);
    add(i << 1 | 1, T[i].bjj);
    T[i].bjj = 0;
  }
  void build(int i, int l, int r) {
    T[i].l = l;
    T[i].r = r;
    T[i].bjc = 1, T[i].cnt.resize(40);
    if (l == r) {
      T[i].sm = A[l];
      T[i].min = A[l];
      T[i].max = A[l];
      T[i].oor = A[l];
      T[i].andd = A[l];
      if (A[l] < 40) T[i].cnt[A[l]] = 1;
      return;
    }
    int M = l + r >> 1;
    build(i << 1, l, M);
    build(i << 1 | 1, M + 1, r);
    pushup(i);
  }
  long long querySum(int i, int l, int r) {
    if (l <= T[i].l && T[i].r <= r) return T[i].sm;
    int M = T[i].l + T[i].r >> 1;
    long long ans = 0;
    pushdown(i);
    if (l <= M) ans += querySum(i << 1, l, r);
    if (r > M) ans += querySum(i << 1 | 1, l, r);
    return ans;
  }
  void queryCount(int i, int l, int r, vector<int>& cnt) {
    if (l <= T[i].l && T[i].r <= r) {
      for (int j = (1); j <= (40); j++) cnt[j - 1] += T[i].cnt[j - 1];
      return;
    }
    int M = T[i].l + T[i].r >> 1;
    pushdown(i);
    if (l <= M) queryCount(i << 1, l, r, cnt);
    if (r > M) queryCount(i << 1 | 1, l, r, cnt);
    return;
  }
  long long queryOr(int i, int l, int r) {
    if (l <= T[i].l && T[i].r <= r) return T[i].oor;
    int M = T[i].l + T[i].r >> 1;
    long long ans = 0;
    pushdown(i);
    if (l <= M) ans = queryOr(i << 1, l, r);
    if (r > M) ans |= queryOr(i << 1 | 1, l, r);
    return ans;
  }
  long long queryAnd(int i, int l, int r) {
    if (l <= T[i].l && T[i].r <= r) return T[i].andd;
    int M = T[i].l + T[i].r >> 1;
    long long ans = 0;
    pushdown(i);
    bool set = false;
    if (l <= M) ans = queryAnd(i << 1, l, r), set = true;
    if (r > M)
      ans =
          set ? (ans & queryAnd(i << 1 | 1, l, r)) : queryAnd(i << 1 | 1, l, r);
    return ans;
  }
  long long queryMax(int i, int l, int r) {
    if (l <= T[i].l && T[i].r <= r) return T[i].max;
    int M = T[i].l + T[i].r >> 1;
    long long ans = llmin;
    pushdown(i);
    if (l <= M) ans = max(ans, queryMax(i << 1, l, r));
    if (r > M) ans = max(ans, queryMax(i << 1 | 1, l, r));
    return ans;
  }
  long long queryMin(int i, int l, int r) {
    if (l <= T[i].l && T[i].r <= r) return T[i].min;
    int M = T[i].l + T[i].r >> 1;
    long long ans = llmax;
    pushdown(i);
    if (l <= M) ans = min(ans, queryMin(i << 1, l, r));
    if (r > M) ans = min(ans, queryMin(i << 1 | 1, l, r));
    return ans;
  }
  void addnew(int i, TT x) {
    T[i].sm = dv[T[i].sm];
    T[i].bjj = 0;
    T[i].max = T[i].sm;
    T[i].min = T[i].sm;
    return;
  }
  void add(int i, int l, int r, TT x) {
    if (l <= T[i].l && T[i].r <= r) {
      add(i, x);
      return;
    }
    int M = T[i].l + T[i].r >> 1;
    pushdown(i);
    if (l <= M) add(i << 1, l, r, x);
    if (r > M) add(i << 1 | 1, l, r, x);
    pushup(i);
  }
  void mul(int i, int l, int r, TT x) {
    if (l <= T[i].l && T[i].r <= r) {
      mul(i, x);
      return;
    }
    int M = T[i].l + T[i].r >> 1;
    pushdown(i);
    if (l <= M) mul(i << 1, l, r, x);
    if (r > M) mul(i << 1 | 1, l, r, x);
    pushup(i);
  }
};
struct less_than_key {
  inline bool operator()(const string& struct1, const string& struct2) {
    return (struct1.size() > struct2.size());
  }
};
long long func(long long n, long long m, long long r, long long x,
               long long y) {
  long long val =
      (min(n + 1, x + r) - max(x, r)) * (min(m + 1, y + r) - max(y, r));
  return val;
}
class triplet {
 public:
  long long x, y, val;
  triplet(long long _x, long long _y, long long _val)
      : x(_x), y(_y), val(_val){};
  inline bool operator<(const triplet& other) const { return val < other.val; }
};
bool sortbysec(const pair<int, int>& a, const pair<int, int>& b) {
  return (a.second < b.second);
}
const long long MAX_VALUE = 1LL * 1000 * 1000 * 1000 * 1000 * 1000 * 1000;
int ans = 0;
int n, m;
vector<int> edges[100001];
vector<int> ar;
bool DFS(int vtx, int cons, int par) {
  if (edges[vtx].size() == 1 && vtx != 1) {
    ans++;
    return true;
  }
  for (auto& ch : edges[vtx]) {
    if (ar[ch] + cons <= m && ch != par) {
      if (ar[ch] == 1)
        DFS(ch, ar[ch] + cons, vtx);
      else
        DFS(ch, 0, vtx);
    }
  }
  return true;
}
bool isPrime(long long x) {
  if (x <= 4 || x % 2 == 0 || x % 3 == 0) return x == 2 || x == 3;
  for (long long i = 5; i * i <= x; i += 6)
    if (x % i == 0 || x % (i + 2) == 0) return 0;
  return 1;
}
long long fac[41];
long long bill = 1000000000;
long long dp[101][101];
int b[100001];
int main() {
  std::cin.sync_with_stdio(false);
  std::cin.tie(nullptr);
  bool test = false;
  if (test) freopen("/Users/aj/code/HackerRank/input.txt", "r", stdin);
  int n;
  cin >> n;
  set<int> st;
  int mx = 0;
  for (int i = (1); i <= (2 * n); i++) {
    int v;
    cin >> v;
    if (st.find(v) == st.end())
      st.emplace(v);
    else
      st.erase(v);
    if (st.size() > mx) mx = st.size();
  }
  cout << mx;
}

```