# import sys

# for line in sys.stdin:
#     a = line.split()
#     print(int(a[0]) + int(a[1]))

import sys


def  solver():
    n= int(input())
    prices=list(map(int,input().split()))
    dp0 =0   #  不持有
    dp1= -prices[0] # 持有
    for i in range(1,len(prices)):
        new_dp0=max(dp0,dp1+prices[i])
        new_dp1=max(dp0-prices[i],dp1)
        dp0=new_dp0
        dp1=new_dp1
    print(dp0)   # 最后不持有 
solver()