import java.util.Scanner;

public class Main {

	@SuppressWarnings("resource")
	public static void main(String args[]) {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		int m = scanner.nextInt();
		int x = scanner.nextInt();
		int a[] = new int[n + 1];

		for (int i = 0; i < m; i++) {
			a[scanner.nextInt()] = 1;
		}

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

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

		System.out.println(Math.min(left, right));
	}
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz