贪心

#include <iostream>

using namespace std;

const int N = 100005;
int a[N], n;

int main()
{
    cin >> n;
    for(int i = 1; i <= n; i++) cin >> a[i];

    int res = 0;

    for(int i = 1; i < n; i++)
    {
        res += max(0, a[i + 1] - a[i]); //在第a天买入，b天卖出，相当于在a,b之间，一天买入下一天就卖出
        //利润大于等于零就卖出一定比小于零卖出的利润更高
    }

    cout << res << endl;

    return 0;
}