N = int(input())*2
cards = list(map(int, input().split()))
homura = 0
tempura = 0
homura_select = 0
for i in range(N):
    if i % 2 == 0:
        if cards[0] > cards[-1]:
            homura += cards[0]
            cards.pop(0)
            homura_select = 0
        else:
            homura += cards[-1]
            cards.pop(-1)
            homura_select = -1
    else:
        tempura += cards[homura_select]
        cards.pop(homura_select)
ans = homura - tempura
print(ans)