#include <bits/stdc++.h>
using namespace std;
int n;
long long ans;
priority_queue<int> q;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9')
    x = (x << 3) + (x << 1) + ch - 48, ch = getchar();
  return x * f;
}
int main() {
  n = read();
  for (int i = 1; i <= n; i++) {
    int num = read();
    q.push(num);
    if (num < q.top()) {
      ans += q.top() - num;
      q.pop();
      q.push(num);
    }
  }
  printf("%lld\n", ans);
}
