n = int(eval(input()))

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



b = [abs(i) for i in a]



if (sum([i < 0 for i in a]) + sum([i == 0 for i in a])) % 2 == 0:

    print((sum(b)))

else:

    print((sum(b) - min(b) * 2))
n = int(eval(input()))

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



b = [abs(i) for i in a]



if sum([i <= 0 for i in a]) % 2 == 0:

    print((sum(b)))

else:

    print((sum(b) - min(b) * 2))
n = int(eval(input()))
a = list(map(int, input().split()))
b = [abs(i) for i in a]
if (sum([i < 0 for i in a]) + sum([i == 0 for i in a])) % 2 == 0:
    print((sum(b)))
else:
    print((sum(b) - min(b) * 2))

n = int(eval(input()))
a = list(map(int, input().split()))
b = [abs(i) for i in a]
if sum([i <= 0 for i in a]) % 2 == 0:
    print((sum(b)))
else:
    print((sum(b) - min(b) * 2))

-if (sum([i < 0 for i in a]) + sum([i == 0 for i in a])) % 2 == 0: +if sum([i <= 0 for i in a]) % 2 == 0: