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