#include <bits/stdc++.h>
using namespace std;
long long inline gcd(long long x, long long y) {
  return !y ? (long long)abs(x) : gcd(y, x % y);
}
long long inline lcm(long long a, long long b) {
  return ((long long)abs((a / gcd(a, b)) * b));
}
double inline cartesian_dist(double x1, double y1, double x2, double y2) {
  return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
long long bigmod(long long b, long long p, long long m) {
  if (!p)
    return 1 % m;
  else if (p & 1)
    return (((b % m) + m) % m * bigmod(b, p - 1, m)) % m;
  else {
    long long ret = bigmod(b, p / 2, m);
    return (ret * ret) % m;
  }
}
long long inverse(long long a, long long m) { return bigmod(a, m - 2, m); }
long long extended(long long a, long long m) {
  long long oldr = a, r = m, oldans = 1, ans = 0, quotient;
  while (r) {
    quotient = oldr / r;
    oldr = oldr - r * quotient;
    swap(oldr, r);
    oldans = oldans - ans * quotient;
    swap(oldans, ans);
  }
  return ((oldans % m) + m) % m;
}
const double PI = acos(-1.0);
const double eps = 10E-12;
const long long MOD = 101LL;
const int inf = 1e7 + 5;
int n, arr[3 * (int)1e5 + 5];
char used[(int)1e6 + 5];
long long calculate() {
  long long ret = 0;
  priority_queue<pair<int, int> > pq;
  while (n >= 1) {
    if (!pq.empty()) {
      if (arr[n] < pq.top().first) {
        ret += pq.top().first - arr[n];
        used[n] ^= 1;
        pq.push(make_pair(arr[n], n));
        used[pq.top().second] ^= 1;
        if (used[pq.top().second]) pq.pop();
      } else
        pq.push(make_pair(arr[n], n));
    } else
      pq.push(make_pair(arr[n], n));
    --n;
  }
  return ret;
}
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) scanf("%d", &arr[i]);
  printf("%lld", calculate());
  printf("\n");
  return 0;
}
