#include <bits/stdc++.h>
#define int long long
using namespace std;
int n, a[300005], ans;
struct node {
	int num;
	bool operator<(const node& p)const {
		return num > p.num;
	}
};
priority_queue<node> que, q;
signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
	}
	for (int i = 1; i <= n; i++) {
		bool flg = false;
		int u, v;
		u = v = 0;
		if (q.size()) {
			if (q.top().num < a[i]) {
				u = a[i] - q.top().num;
			}
		}
		if (que.size()) {
			if (que.top().num < a[i]) {
				v = a[i] - que.top().num;
			}
		}
		if (u == 0 && v == 0) {
			q.push(node{a[i]});
		} else if (u > v) {
			ans += u;
			q.pop();
			que.push(node{a[i]});
		} else {
			ans += v;
			q.push(que.top());
			que.pop();
			que.push(node{a[i]});
		}
	}
	cout << ans;
}