import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] sa = br.readLine().split(" ");
		int n = Integer.parseInt(sa[0]);
		StringBuilder sb0 = new StringBuilder();
		StringBuilder sb1 = new StringBuilder();
		for (int i = 0; i < n; i++) {
			sa = br.readLine().split(" ");
			if (sa[0].equals("0")) {
				sb0.append(sa[1]);
			} else {
				sb1.append(sa[1]);
			}
		}
		br.close();

		sb1.reverse();
		sb1.append(sb0);
		System.out.println(sb1.toString());
	}
}