#include<bits/stdc++.h>
using namespace std;
#define int long long
int n;
int a[1000005];
/*
I’m all by myself seen this show like a thousand times
It’s a side effect loneliness without no reply
In my mind I just keep pretending it’s a big old lie
Big old lie big old lie
Dancing on the tables city full of angels
Dreams of diamonds and gold
All the different faces ones I used to hate
I miss them now that they’re gone
Oh my God did we go too far
Did we waste it all like we’re running out of roses
Plastic cups did we laugh enough
Looking back on us now that everything is over
Oh my God did we go too far
Did we waste it all like we’re running out of roses
Plastic cups did we laugh enough
Looking back on us now that everything is over
On a night like this
All I know is what I should’ve said
In the life I’ve lived
All the things I wanna do again
When the silence sings
Swear I’ll never let a day go by
Day go by day go by
Dancing on the tables city full of angels
Dreams of diamonds and gold
All the different faces ones I used to hate
I miss them now that they’re gone
Oh my God did we go too far
Did we waste it all like we’re running out of roses
Plastic cups did we laugh enough
Looking back on us now that everything is over
Oh my God did we go too far
Did we waste it all like we’re running out of roses
Plastic cups did we laugh enough
Looking back on us now that everything is over
*/
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>>a[i];
    int ans = 0;
    for(int i = 1;i<=n;i++){
        if(!q.empty() and q.top()<=a[i]){
            ans+=a[i]-q.top();q.pop();q.push(a[i]);
        }q.push(a[i]);
    }cout<< ans<<endl;
    return 0;
}