Envío 1500

Código

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        boolean loop = false;

        int [] a = new int[n];
        for (int i = 0; i < n; i++) {
            a[i] = sc.nextInt();
        }

        int left = 0, right = 0;
        for (int i = 0; i < n; i++) {
            right += a[i];
        }

        for (int p = 0; p < n; p++) {
            if (left > 0 && right < 0) {
                System.out.println(p);
                loop = true;
                break;
            }
            left += a[p];
            right -= a[p];
        }
        if (!loop) {
            System.out.println("Impossible");
        }
	}
}