N = int(input())
C = list(map(int, input().split()))

if 0 <= C[0] and 0 <= C[-1]:
    print(C[-1]*2)
elif C[0] < 0 and C[-1] < 0:
    print((-C[0])*2)
else:
    print(C[-1]*2+(-C[0])*2)