N = int(input())
A = list(map(int, input().split()))
S = [[0, 0]]
for i in range(N):
    S.append([0, 0])
    S[i + 1][0] = max(S[i][0], S[i][1] + A[i])
    S[i + 1][1] = max(S[i][1], S[i][0] - A[i])
print(max(S[N][0], S[N][1]))