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