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

inf = -1<<60

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

ans = inf
for i in range(N):
    if i == 0: #必ずマイナス側しか選ぶことができない
        dp[i+1][1] = max(dp[i][0] -A[i], dp[i][1])
    else:
        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]))