
    In a hospital's patient monitoring system, where risk scores from multiple medical evaluations are recorded, develop a function to identify the unique risk factor that was detected only once in the sorted assessment data. All other risk factors have been confirmed by two separate evaluations, making this single occurrence particularly important for immediate medical review. The risk scores are maintained in ascending order for efficient processing.
    

    
def search(arr):
    """
    In a hospital's patient monitoring system, where risk scores from multiple medical evaluations are recorded, develop a function to identify the unique risk factor that was detected only once in the sorted assessment data. All other risk factors have been confirmed by two separate evaluations, making this single occurrence particularly important for immediate medical review. The risk scores are maintained in ascending order for efficient processing.
    

    """
def search(arr):
    """
    In a hospital's patient monitoring system, where risk scores from multiple medical evaluations are recorded, develop a function to identify the unique risk factor that was detected only once in the sorted assessment data. All other risk factors have been confirmed by two separate evaluations, making this single occurrence particularly important for immediate medical review. The risk scores are maintained in ascending order for efficient processing.
    

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