import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Back_1037 {
    public static void main(String[] args) throws IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int T = Integer.parseInt(br.readLine());

        int max = Integer.MIN_VALUE;
        int min = Integer.MAX_VALUE;

        StringTokenizer st = new StringTokenizer(br.readLine()," ");

        while(T-- > 0){
            int N = Integer.parseInt(st.nextToken());
            max = N > max ? N : max;
            min = N < min ? N : min;
        }
        System.out.println(max * min);
    }
}