#include<bits/stdc++.h>
using namespace std;
const int N=1e6+4;
long long a[N],n;
int main()
{
cin>>n;
for(int i=1;i<=n;i++) cin>>a[i];
long long dem=0;
sort(a+1,a+n+1);
for(int i=2;i<=n;i++)
{
if(a[i]-a[i-1]>1) dem=dem+a[i]-a[i-1]-1;
}
cout<<dem;
}
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