include <bits/stdc++.h>

using namespace std;

int main() {

list<int>a1;
int x;
cin >> x;
while (x != -1) {
	a1.push_back(x);
	cin >> x;
}
cin >> x;
while (x != -1) {
	a1.push_back(x);
	cin >> x;
}
a1.sort();
for (auto k = a1.begin(); k != a1.end(); k++) {
	cout << *k << " ";
}

return 0;

}