#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  long long int a[n];
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  long long int c = 0;
  for (int i = 1; i < n; i++) {
    if (a[i] != (a[i - 1] + 1)) {
      c += (a[i] - a[i - 1] - 1);
    }
  }
  cout << c << endl;
}
