#include <bits/stdc++.h>
using namespace std;
int n, a[100], sum = 0;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  for (int i = 0; i < n - 1; i++) sum += (a[n - 1] - a[i]);
  cout << sum;
  return 0;
}
