n = int(input())
c = list(map(int,input().split()))

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