#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef unsigned long long ull;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) {
    return (ull)rng() % B;
}

struct SlopeTrick{
	ll res;
	priority_queue<ll> pq;
	SlopeTrick():res(0),pq(){}
	void add(const ll x){
		if(pq.size() and pq.top()>x){
			res+=pq.top()-x;
			pq.pop(); pq.push(x);
		}
		pq.push(x);
	}
};

int main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	int n; cin >> n;
	SlopeTrick slope;
	for(int i=0;i<n;i++){
		int a; cin >> a;
		slope.add(a);
	}
	cout << slope.res << endl;
}