#include <cassert>
#include <iostream>
#include <optional>
#include <string>
#include <string_view>
using namespace std;

const int lookahead = 1;

int main() {

	int n;
	cin >> n;
	string as, bs;
	cin >> as >> bs;
	assert(as.size() == n and bs.size() == n);

	std::string_view a = as, b = bs;

	string ans;
	while(not b.empty()) {
		for(int i = 0; i <= lookahead and i < b.size(); ++i) {
			if(a[0] == b[i]) {
				ans.push_back(a[0]);
				a.remove_prefix(1);
				b.remove_prefix(i + 1);
				goto end;
			}
			if(a[i] == b[0]) {
				ans.push_back(b[0]);
				a.remove_prefix(i + 1);
				b.remove_prefix(1);
				goto end;
			}
		}

		a.remove_prefix(1);
		b.remove_prefix(1);

	end:;
		if(a.size() < b.size()) swap(a, b);
	}
	cout << ans << endl;
	cout.flush();
}