n=int(input())
A=list(map(int,input().split()))
INF=float("inf")
dp=[[-INF]*2 for _ in range(n+1)]
for i in range(n):
    dp[i+1][0]=max(-A[i],dp[i][1]-A[i],dp[i][0])
    dp[i+1][1]=max(dp[i][0]+A[i],dp[i][1])
print(max(dp[-1]))