#include<iostream>
#include<map>
#include<vector>
#include <algorithm>
#include<math.h>
using namespace std;

int main()
{
    int n, cnt = 0;
    cin >> n;
    vector<int> v(n, 0);
    for (int i = 0; i < n; i++){
        int t;
        cin >> t;
        v[t-1]++;
    }
    for (int i = 0; i < n; i++){
        if (v[i] > 1){
            int j = i + 1;
            while (v[i] != 1){
                if (v[j] == 0){
                    cnt += (j - i);
                    v[i]--;
                    v[j]++;
                } else j++;
            }
        } else if (!v[i]){
            for (int j = i; j < n; j++){
                if (v[j] > 1){
                    cnt += (j - i);
                    v[j]--;
                    v[i]++;
                    break;
                }
            }
        }
    }
    cout << cnt << endl;
}