import math

def jumpSearch( arr , x , n ):
	
	step = math.sqrt(n)
	

	prev = 0
	while arr[int(min(step, n)-1)] < x:
		prev = step
		step += math.sqrt(n)
		if prev >= n:
			return -1
	

	while arr[int(prev)] < x:
		prev += 1
		

		if prev == min(step, n):
			return -1
	
	if arr[int(prev)] == x:
		return prev
	
	return -1

arr = list(map(int,input("Enter the array elements: ").split()))
x = int(input("enter the number to search: "))
n = len(arr)

index = jumpSearch(arr, x, n)

print("Number" , x, "is at index" ,"%.0f"%index)