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

INF = 10**18
dp = [[-INF]*2 for _ in range(N+1)]
for i in range(N):
    dp[i+1][1] = -A[i]

for i in range(N):
    if dp[i][0] != -INF:
        dp[i+1][0] = max(dp[i+1][0], dp[i][0])
        dp[i+1][1] = max(dp[i+1][1], dp[i][0]-A[i])
    if dp[i][1] != -INF:
        dp[i+1][1] = max(dp[i+1][1], dp[i][1])
        dp[i+1][0] = max(dp[i+1][0], dp[i][1]+A[i])

print(max(dp[-1]))