def lonelyinteger(a): 
    # Write your code here
    
    count_dict = {} # Initialize an empty dictionary
    for item in a:
        if item in count_dict:
            count_dict[item] += 1  
            # Increment the count if item is already in dictionary
        else:
            count_dict[item] = 1   
            # Add the item with count 1 if it's not in the dictionary
    return [key for key, value in count_dict.items() if value == 1]
    
    
if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    n = int(input().strip())

    a = list(map(int, input().rstrip().split()))

    result = lonelyinteger(a)

    fptr.write(' '.join(map(str,result)) + '\n')

    fptr.close()