N = int(input())
A = list(map(int,input().split()))
inf = 10 ** 20

dp = [[-inf] * 2 for _ in range(N)]
dp[0][1] = -A[0]

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