#include <iostream>

using namespace std;

const int N = 1e5 + 10;

int n;
int price[N];

int main()
{
    cin >> n;
    for (int i = 0; i < n; i ++ ) cin >> price[i];

    int profit = 0;
    for (int i = 1; i < n; i ++ )
        if (price[i] > price[i - 1])            //仔细想想
            profit += price[i] - price[i - 1];  //只要当前股价大于前一天，利润就增加大于的差值

    cout << profit << endl;
}