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