
    In a sorted list of passenger counts collected from bus stops across the city's bi-directional routes, identify the unique passenger count that represents a terminal stop requiring special attention for route optimization, given that all other stops appear exactly twice in the data due to their bi-directional nature. The passenger counts are collected in ascending order, and there is guaranteed to be exactly one unique count in the dataset.
    

    
def search(arr):
    """
    In a sorted list of passenger counts collected from bus stops across the city's bi-directional routes, identify the unique passenger count that represents a terminal stop requiring special attention for route optimization, given that all other stops appear exactly twice in the data due to their bi-directional nature. The passenger counts are collected in ascending order, and there is guaranteed to be exactly one unique count in the dataset.
    

    """
def search(arr):
    """
    In a sorted list of passenger counts collected from bus stops across the city's bi-directional routes, identify the unique passenger count that represents a terminal stop requiring special attention for route optimization, given that all other stops appear exactly twice in the data due to their bi-directional nature. The passenger counts are collected in ascending order, and there is guaranteed to be exactly one unique count in the dataset.
    

    """
    n = len(arr)
    XOR = 0
    for i in range(n):
        XOR = XOR ^ arr[i]
    return XOR