import java.io.*;

class GFG {

	// Function to check if an array is
	// Sorted and rotated clockwise
	static boolean checkIfSortRotated(int arr[], int n)
	{
		// Initializing two variables x,y as zero.
		int x = 0, y = 0;

		// Traversing array 0 to last element.
		// n-1 is taken as we used i+1.
		for (int i = 0; i < n - 1; i++) {
			if (arr[i] < arr[i + 1])
				x++;
			else
				y++;
		}

		// If till now both x,y are greater
		// then 1 means array is not sorted.
		// If both any of x,y is zero means
		// array is not rotated.
		if (x == 1 || y == 1) {
			// Checking for last element with first.
			if (arr[n - 1] < arr[0])
				x++;
			else
				y++;

			// Checking for final result.
			if (x == 1 || y == 1)
				return true;
		}
		// If still not true then definitely false.
		return false;
	}

	// Driver code
	public static void main(String[] args)
	{
		int arr[] = { 5, 1, 2, 3, 4 };

		int n = arr.length;

		// Function Call
		boolean x = checkIfSortRotated(arr, n);
		if (x == true)
			System.out.println("YES");
		else
			System.out.println("NO");
	}
}