N = int(input())
num_list = []
for i in range(N):
    s = int(input())
    num_list.append(s)
x_list=[]
y_list=[]
num_list.sort(reverse=True)
while num_list:
    num_list.sort(reverse=True)
    x_list.append(num_list.pop(0))
    num_list =[n*-1 for n in num_list]
    if num_list :
        num_list.sort(reverse=True)
        y_list.append(num_list.pop(0))
        num_list =[n*-1 for n in num_list]

X_sum = sum(x_list)
Y_sum = sum(y_list)

print(X_sum - Y_sum)