Go: package main

import "fmt"

func main() {
    var n, m int
    fmt.Scan(&n)

    u := make([]string, 300)

    for i := 0; i < n; i++ {
        fmt.Scan(&u[i])
    }

    fmt.Scan(&m)

    is_lock := true
    for i := 0; i < m; i++ {
        var t string
        fmt.Scan(&t)

        is_include := false
        for j := 0; j < n; j++ {
            if t == u[j] {
                is_include = true
                break
            }
        }
        if is_include == false {
            fmt.Printf("Unknown %s\n", t)
        } else if (is_lock) {
            fmt.Printf("Opened by %s\n", t)
            is_lock = false
        } else {
            fmt.Printf("Closed by %s\n", t)
            is_lock = true
        }
    }
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <functional>
#include <numeric>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <utility>
#include <sstream>
#include <complex>

using namespace std;

#define FOR(i,a,b) for(long long i=(a);i<(b);i++)
#define REP(i,N) for(long long i=0;i<(N);i++)
#define ALL(s) (s).begin(),(s).end()
#define fi first
#define se second

#define PI acos(-1.0)
#define INF 1000000007
#define EPS 1e-10
#define MAX_M 100100

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<double, double> PD;
typedef pair<string, ll> PS;
typedef vector<ll> V;
typedef pair<P, char> PC;

int n, m;
string u;
vector<string> vs;

int main(){
	bool f = 0;
	cin >> n;
	REP(i, n){
		cin >> u;
		vs.push_back(u);
	}
	cin >> m;
	REP(i, m){
		cin >> u;
		if (find(ALL(vs), u) == vs.end()){
			cout << "Unknown " << u << endl;
		}
		else{
			if (!f)cout << "Opened by " << u << endl;
			else cout << "Closed by " << u << endl;
			f = !f;
		}
	}
}

C++: #include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <cfloat>
#include <ctime>
#include <cassert>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <numeric>
#include <list>
#include <iomanip>
#include <fstream>
#include <bitset>
   
using namespace std;
   
 
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define foreach(it, c) for (__typeof__((c).begin()) it=(c).begin(); it != (c).end(); ++it)
#define rforeach(it, c) for (__typeof__((c).rbegin()) it=(c).rbegin(); it != (c).rend(); ++it)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define CL(arr, val) memset(arr, val, sizeof(arr))
#define COPY(dest, src) memcpy(dest, src, sizeof(dest))
#define ten(n) ((long long)(1e##n))
#define bin(n) (1LL << (n))
#define erep(i, n) for (int i = 0; i <= (int)(n); ++i)
#define revrep(i, n) for (int i = (n); i >= 0; --i)
#define pb push_back

template <class T> void chmax(T& a, const T& b) { a = max(a, b); }
template <class T> void chmin(T& a, const T& b) { a = min(a, b); }

template <class T> void uniq(T& c) { sort(c.begin(), c.end()); c.erase(unique(c.begin(), c.end()), c.end()); }
 
template <class T> string to_s(const T& a) { ostringstream os; os << a; return os.str(); }
template <class T> T to_T(const string& s) { istringstream is(s); T res; is >> res; return res; }

template <typename T> void print_container(ostream& os, const T& c) { const char* _s = " "; if (!c.empty()) { __typeof__(c.begin()) last = --c.end(); foreach (it, c) { os << *it; if (it != last) cout << _s; } } }
template <typename T> ostream& operator<<(ostream& os, const vector<T>& c) { print_container(os, c); return os; }
template <typename T> ostream& operator<<(ostream& os, const set<T>& c) { print_container(os, c); return os; }
template <typename T> ostream& operator<<(ostream& os, const multiset<T>& c) { print_container(os, c); return os; }
template <typename T> ostream& operator<<(ostream& os, const deque<T>& c) { print_container(os, c); return os; }
template <typename T, typename U> ostream& operator<<(ostream& os, const map<T, U>& c) { print_container(os, c); return os; }
template <typename T, typename U> ostream& operator<<(ostream& os, const pair<T, U>& p) { os << "( " << p.first << ", " << p.second << " )"; return os; }

template <class T> void print(T a, int n, const string& deli = " ", int br = 1) { for (int i = 0; i < n; ++i) { cout << a[i]; if (i + 1 != n) cout << deli; } while (br--) cout << endl; }
template <class T> void print2d(T a, int w, int h, int width = -1, int br = 1) { for (int i = 0; i < h; ++i) { for (int j = 0; j < w; ++j) {    if (width != -1) cout.width(width); cout << a[i][j] << ' '; } cout << endl; } while (br--) cout << endl; }

template <class T> void input(T& a, int n) { for (int i = 0; i < n; ++i) cin >> a[i]; }
template <class T> void input(T* a, int n) { for (int i = 0; i < n; ++i) cin >> a[i]; }

void fix_pre(int n) { cout.setf(ios::fixed, ios::floatfield); cout.precision(10); }
void fast_io() { cin.tie(0); ios::sync_with_stdio(false); }
#define trace(x) (cout << #x << ": " << (x) << endl)
 
bool in_rect(int x, int y, int w, int h) { return 0 <= x && x < w && 0 <= y && y < h; }


typedef long long ll;
typedef pair<int, int> pint;
 
// y(v): v>^<  y(^): ^>v<
const int dx[] = { 0, 1, 0, -1 };
const int dy[] = { 1, 0, -1, 0 };

const double PI = acos(-1.0);
#define mp make_pair



int main()
{
    map<string, bool> reg;
    int n;
    cin >> n;
    while (n--)
    {
        string id;
        cin >> id;
        reg[id] = true;
    }
    
    bool closed = true;
    int m;
    cin >> m;
    while (m--)
    {
        string id;
        cin >> id;
        if (reg.count(id))
        {
            cout << (closed ? "Opened" : "Closed") << " by " << id << endl;
            closed ^= true;
        }
        else
            cout << "Unknown " << id << endl;
    }
}

C++: #include <iostream>
#include <string>
#include <map>
using namespace std;

int main(){
  string s[256];
  string sta;
  int n,m;
  int fl = 1;
  bool judge;
  cin >> n;
  for(int i=0;i<n;i++){
    cin >> s[i];
  }
  cin >> m;
  for(int i=0;i<m;i++){
    cin >> sta;
    judge = false;
    for(int j=0;j<n;j++){
      if(sta == s[j] && fl == 1){
	cout << "Opened by " << s[j] << endl;
	fl = 0;
	judge = true;
      }
      else if(sta == s[j] && fl == 0){
	cout << "Closed by " << s[j] << endl;
	fl = 1;
	judge = true;
      }
    }
    if(!judge) cout << "Unknown " << sta << endl;
  }

}

C++: #include<iostream>
#include<string>
#include<set>
#include<algorithm>

using namespace std;

int main(){
  int i, n, m;
  string id;
  bool is_open;
  set<string> data;

  cin >> n;
  for(i=0; i<n; ++i){
    cin >> id;
    data.insert(id);
  }

  cin >> m;
  for(i=0, is_open=false; i<m; ++i){
    cin >> id;
    if(data.find(id) != data.end()){
      if(is_open == false){
	cout << "Opened by " << id << endl;
	is_open = true;
      }else{
	cout << "Closed by " << id << endl;
	is_open = false;
      }
    }else{
      cout << "Unknown " << id << endl;
    }
  }

  return 0;
}