n=int(input())
a=list(map(int,input().split()))
dp0=[-10**15]
dp1=[-10**15]
for i in range(n):
  dp0.append(max(0,dp0[-1],dp1[-1]+a[i],a[i]))
  dp1.append(max(0,dp1[-1],dp0[-1]-a[i],-a[i]))
print(max(0,dp0[-1],dp1[-1]))