#include<bits/stdc++.h>
using namespace std;
const int MAXLEN=300005;
int n,p[MAXLEN],ans=0;
priority_queue<int, vector<int> ,greater<int> > q;
signed main(){
	ios::sync_with_stdio(0);
	cin.tie(0),cout.tie(0);
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>p[i];
	}
	for(int i=1;i<=n;i++){
		q.push(p[i]);
		if(!q.empty()&&q.top()<p[i]){
			ans+=p[i]-q.top();
			q.pop();
			q.push(p[i]);
		}
	}cout<<ans;
	return 0;
}

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