include <bits/stdc++.h>

using namespace std; map<int,int> a;

int main() {

int t;
cin>>t;
while(t!=-1) {
	if(a.find(t)==a.end()) {
		a[t]=0;
	}
	a[t]++;
	cin>>t;
}
cin>>t;
while(t!=-1) {
	if(a.find(t)==a.end()) {
		a[t]=0;
	}
	a[t]++;
	cin>>t;
}
for(auto it=a.begin(); it!=a.end(); it++) {
	while((*it).second!=0) {
		cout<<(*it).first<<" ";
		(*it).second--;
	}
}
return 0;

}