#include
#include
#include
using namespace std;
#include
#include
#include
#include
using namespace std;
const int N = 1e4;
int a[N];
int main()
{
int n;
int cnt=0;
cin >> n;
for (int i = 0; i < n; i ++ )
cin >> a[i];
sort(a,a+n);
for (int i = 1; i < n; i ++ )
{
while(a[i]<=a[i-1])
{
cnt++;
a[i]++;
}
}
cout<
import java.io.*;
import java.util.Arrays;
import java.util.Scanner;
public class Main {
private static int[] a=new int[3001];
public static void main(String[] args) {
int cnt=0;
Scanner reader=new Scanner(System.in);
int n=reader.nextInt();
for (int i = 0; i < n; i++) {
a[i]= reader.nextInt();
}
Arrays.sort(a,0,n);
for (int i = 1; i < n; i++) {
while (a[i]<=a[i-1])
{
cnt++;
a[i]++;
}
}
System.out.println(cnt);
}
}