# 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()