N = int(input())
A = [0]+list(map(int,input().split()))
INFTY = 10**10
dp = [[-INFTY for _ in range(2)] for _ in range(N+1)]
dp[1][0] = -A[1]
for i in range(2,N+1):
    dp[i][1] = max(dp[i-1][1],dp[i-1][0]+A[i])
    dp[i][0] = max(dp[i-1][0],dp[i-1][1]-A[i],-A[i])
print(max(dp[N][0],dp[N][1]))