#include <bits/stdc++.h>
#pragma GCC optimize(3, "Ofast", "inline")
using namespace std;
long long qpow(long long a, long long b) {
  long long res = 1;
  while (b) {
    if (b & 1) res = res * a;
    a = a * a;
    b >>= 1;
  }
  return res;
}
long long qpow(long long a, long long b, long long mod) {
  long long res = 1;
  while (b) {
    if (b & 1) res = res * a % mod;
    a = a * a % mod;
    b >>= 1;
  }
  return res;
}
long long inv(long long a, long long mod) { return qpow(a, mod - 2, mod); }
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long lcm(long long a, long long b) { return a * b / gcd(a, b); }
template <typename T>
inline void read(T &x) {
  x = 0;
  T f = 1;
  char c = getchar();
  for (; !isdigit(c); c = getchar())
    if (c == '-') f = -1;
  for (; isdigit(c); c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
  x *= f;
}
template <typename T>
inline void write(T x) {
  if (x < 0) {
    putchar('-');
    x = -x;
  }
  if (x > 9) write(x / 10);
  putchar(x % 10 + '0');
}
const double eps = 1e-10;
const long long inf = 0x3f3f3f3f, base = 137, mod = 1e9 + 7;
const int N = 3e5 + 5, M = 50 + 5, S = 1e6 + 5;
int p[N];
priority_queue<int, vector<int>, greater<int> > q;
void solve() {
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) scanf("%d", &p[i]);
  long long ans = 0;
  for (int i = 1; i <= n; i++) {
    q.push(p[i]);
    int x = q.top();
    if (p[i] - x > 0) {
      q.pop();
      ans += p[i] - x;
      q.push(p[i]);
    }
  }
  cout << ans << endl;
}
int main() {
  int T = 1;
  while (T--) {
    solve();
  }
}
