N = int(input())
C = list(map(int, input().split()))
ans = 0
if C[0] < 0 and C[-1] > 0:
    ans = -C[0] * 2 + C[-1] * 2
elif C[0] < 0:
    ans = -C[0] * 2
else:
    ans = C[-1] * 2
print(ans)