def bin_search(arr:list,low:int,high:int,k:int)->bool:
if low <= high:
mid = (high + low) // 2
if (mid == k):
return True
elif arr[mid] < k:
return(bin_search(arr,mid+1,high,k))
else:
return(bin_search(arr,low,mid-1,k))
else:
return False
def find_number(arr:list,k:int)->bool:
return(bin_search(arr,0,len(arr)-1,k))
