N = int(input())
A = list(map(int, input().split()))
max_ = max(A)
for i in range(N):
    if A[i]<0:
        if A[i]*-1<max_:
            A[i] = max_
    else:
        A[i] = max_
sum_ = 0
for v in A:
	sum_ += abs(v)

print(sum_)