def ss(C):
    if len(C) < 10 or len(C) > 12:
        return C[-1]
    F = C[:3]
    if len(set(F)) != 3 or not all(c.isupper() for c in F):
        return C[-1]
    Y = C[3:7]
    if not Y.isdigit() or not (1900 <= int(Y) <= 2019):
        return C[-1]
    D = C[7:-1]
    v = {'10', '20', '50', '100', '200', '500', '1000'}
    if D not in v:
        return C[-1]
    l = C[-1]
    if not (l.isupper() and len(l) == 1):
        return C[-1]
    return C[0]

#include <iostream>
#include <vector>
#include <iomanip>
#include <numeric>
#include <string>
#include <sstream>
using namespace std;
string largestSegment(vector<int> radii, int segments) {
    const double pi = 3.14159265359;
    int n = radii.size();
    vector<double> areas(n);
    
    for (int i = 0; i < n; ++i) {
        areas[i] = pi * radii[i] * radii[i];
    }

    double totalArea = accumulate(areas.begin(), areas.end(), 0.0);
    double low = 0, high = totalArea / segments;

    auto canCutSegments = [&](double x) {
        int count = 0;
        for (double area : areas) {
            count += static_cast<int>(area / x);
        }
        return count >= segments;
    };

    while (high - low >= 1e-4) {
        double mid = (low + high) / 2;
        if (canCutSegments(mid)) {
            low = mid;
        } else {
            high = mid;
        }
    }

    stringstream ss;
    ss << fixed << setprecision(4) << low;
    return ss.str();
}

#include <iostream>
#include <vector>
#include <string>

using namespace std;

long long getTotalPalindromeTransformationCost(const string& s) {
    int mask = 0;
    int n = s.length();
    vector<int> f(26, 0);
    long long ans = 0;

    for (int i = 0; i < n; i++) {
        mask ^= 1 << (s[i] - 'a'); 
        int cnt = 0;

        for (int j = 0; j < 26; j++) {
            if (mask & (1 << j)) {
                cnt += i + 1 - f[j];
                f[j] += 1; 
            } else {
                cnt += f[j]; 
            }
        }

        ans += (cnt - (i + 2) / 2) / 2;
    }

    return ans;
}

#include <bits/stdc++.h>
using namespace std;
long long binomialCoeff(int n, int k) {
    long long res = 1;
    if (k > n - k)
        k = n - k;

    for (int i = 0; i < k; ++i) {
        res *= (n - i);
        res /= (i + 1);
    }

    return res;
}

long long catalanNumber(int k) {
    long long c = binomialCoeff(2 * k, k);
    return c / (k + 1);
}

int main() {
    int n;
    cin >> n;

    long long result = catalanNumber(n - 1);
    
    cout << result << endl;

    return 0;
}

#include<iostream>
using namespace std;
int t,a[200010],n,k;
int main(){
cin>>t;
while(t--){
  cin>>n>>k;
  int l=1,r=n;
  for(int j=1;j<=k;j++){
   for(int i=j;i<=n;i+=k){
    if(i&1)a[i]=l++;
    else a[i]=r--;
   }
  }
  for(int i=1;i<=n;i++){
   cout<<a[i]<<" ";
  }
  cout<<endl;
}

return 0;
}

#include <iostream>
#include <unordered_map>
#include <vector>
using namespace std;

int ss(int n, vector<int>& arr) {
    unordered_map<int, int> frequency;
        for (int num : arr) {
        frequency[num]++;
    }
    
    int odd_count = 0;
    
    for (auto& pair : frequency) {
        if (pair.second % 2 != 0) {
            odd_count++;
        }
    }
    
    return odd_count / 2;
}

int main() {
    int N;
    cin >> N;
    
    vector<int> arr(N);
    for (int i = 0; i < N; i++) {
        cin >> arr[i];
    }
    
    int result = ss(N, arr);
    cout << result << endl;

    return 0;
}

#include <iostream>
#include <vector>
#include <unordered_set>
using namespace std;
void computeSums(const vector<int>& a, vector<int>& b, int c, int d) {
    if (c == a.size()) {
        b.push_back(d);
        return;
    }

    computeSums(a, b, c + 1, d + a[c]);
    computeSums(a, b, c + 1, d);
}

int main() {
    int e, f;
    cin >> e;

    cin >> f;

    vector<int> g(e);
    for (int h = 0; h < e; h++) {
        cin >> g[h];
    }

    vector<int> i, j;
    computeSums(vector<int>(g.begin(), g.begin() + e / 2), i, 0, 0);
    computeSums(vector<int>(g.begin() + e / 2, g.end()), j, 0, 0);

    unordered_set<int> k(i.begin(), i.end());

    for (int l : j) {
        if (k.count(f - l)) {
            cout << 1 << endl;
            return 0;
        }
    }

    cout << 0 << endl;
    return 0;
}