# H,W,Q=map(int,input().split())\
# A=sorted(A,key=lambda x: x[1])
# A=sorted(A,key=lambda x: x[0])

N=int(input())
A=list(map(int, input().split()))
if N==1:
  print(-A[0])
  exit()
  
dp=[0,-10**15,-10**15]
for i in range(N):
  a=A[i]
  ndp=[0,-10**15,-10**15]
  ndp[1]=max(dp[1],ndp[1],dp[2]-a,dp[0]-a)
  ndp[2]=max(dp[2],ndp[2],dp[1]+a)
  dp=ndp
  #print(dp)
  
ans=max(dp[1],dp[2])
print(ans)