public class Solution {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        int maximum = 0;
        int minimum = -2147483648;
        int N = Integer.parseInt(reader.readLine());

        //напишите тут ваш код
        for (int i = 0; i < N ; i++) {

            int x = Integer.parseInt(reader.readLine());
            if (x >= 0) {
                maximum = maximum > x ? maximum : x;
            }if(x < 0)
                maximum = minimum;
                minimum = minimum > x ? minimum : x;
        }
        System.out.println(maximum);
        }
    }