#include
#include
#include
typedef long long ll;
using namespace std;
void solve(){
int N; cin >> N;
int MAX = 2 * N + 1;
unordered_set s;
int count = 1;
for (int i = 0; i <= N; i++) {
while (s.find(count) != s.end()) count++;
cout << count << endl;
s.insert(count);
int t; cin >> t; if (t == 0) break;
s.insert(t);
}
}
int main(){
solve();
return 0;
}