N = int(input())
A = list(map(int, input().split())) 
DP = [-10**18,-10**18]
for i,a in enumerate(A):
    NDP = [max(DP[0],DP[1]+a) ,max(DP[1],DP[0]-a)]
    DP = NDP
    if DP[1]<-a:
        NDP[1]=-a
print(max(DP))