/*

贪心来选择， 如果能找到比当前小的， 就用最小的来更新当前的

优先队列即可 

*/

#include<cstdio>

#include<algorithm>

#include<cstring>

#include<queue>

#include<iostream>

#define ll long long

#define mmp make_pair

#define M

using namespace std;

int read()

{

	int nm = 0, f = 1;

	char c = getchar();

	for(; !isdigit(c); c = getchar()) if(c == '-') f = -1;

	for(; isdigit(c); c = getchar()) nm = nm * 10 + c - '0';

	return nm * f;

}

priority_queue<ll> q;

ll ans = 0;

int main()

{

	int n = read();

	while(n--)

	{

		int x = read();

		q.push(-x), q.push(-x);

		ans += x + q.top();

		q.pop();

	}

	cout << ans << "\n";

	return 0;

}