#include <bits/stdc++.h>
using namespace std;
int main() {
  long long sum = 0;
  int n;
  cin >> n;
  int a[n];
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  for (int i = 0; i < n; i++) sum += a[n - 1] - a[i];
  cout << sum << endl;
  return 0;
}
