import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n = in.nextInt();
int[] arr = new int[n];
for (int i = 0; i < n; i++) {
arr[i] = in.nextInt();
}
int count = 1;
int max = 1;
for (int i = 1; i < n; i++) {
if (Math.abs(arr[i] - arr[i - 1]) <= 1) {
count++;
} else {
count = 1;
}
if (count > max) {
max = count;
}
}
System.out.println(max);
}
}

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