def binarySearch(v,n):
    """binary search in an ordered vector
    
    Arguments:
        v {vector} -- vector with ordered elements
        n {integer} -- search number
    
    Returns:
        boolean -- true if element exist in list
    """
    l = len(v)
    if l >= 1:
        mid = l//2
        if v[mid]==n:
            return True
        elif v[mid]>n:
            return binarySearch(v[:mid],n)
        elif v[mid]<n:
            return binarySearch(v[mid+1:],n)
    else:
        return False