#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
int main()
{
LL N, tmp, sum = 0, a = 1000001, b = 0;
cin >> N;
for (int i = 0; i < N; ++i) {
cin >> tmp;
a = min(a,tmp);
b = max(b, tmp);
}
cout << (b-a+1 - N);
return 0;
}
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