import java.util.Scanner;

public class NickyEnMark {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		long c = scanner.nextInt();
		long s = 0;
		long[] sums = new long[n];
		for (int i = 0; i < n; i++) {
			s += scanner.nextLong();
			sums[i] = s;
		}

		if (sums[0] >= n * c) {
			System.out.println("impossible");
			return;
		}

		int minimum = 100_001;
		int save = -1;

		for (int i = 0; i < n; i++) {
			int q = (int) Math.max(0, Math.ceil(((sums[i] + 1 - i * c) / (double) c) - 1));
			if (i + q >= n) {
				break;
			} else {
				if (q < minimum) {
					minimum = q;
					save = i;
				}
			}
		}

		System.out.println(save);
	}
}