#include<bits/stdc++.h> using namespace std; int n,prices[10001]; int main() { cin>>n; for(int i=0;i<n;i++) cin>>prices[i]; int buy1=-prices[0],sell1=0; int buy2=-prices[0],sell2=0; for (int i=1;i<n;i++) { buy1= max(buy1, -prices[i]); sell1=max(sell1, buy1+prices[i]); buy2=max(buy2, sell1-prices[i]); sell2=max(sell2, buy2+prices[i]); } cout<<sell2<<endl; return 0; }