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

dp = [[-1, -1] for _ in range(N+1)]
dp[0] = [0, 0]

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


print(max(dp[N]))