CF865D Buy Low Sell High

/*
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;
}