#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;

int main() {

	int n;
	cin >> n;
	vector<int> array;
	array.resize(n + 1, 0);
	for (int i = 0;i<n;i++) {
		int num;
		cin >> num;
		array[num]++;
	}

	int cost = 0;
	bool flag = false;

	while (!flag) {
		int target1 = 0, target2 = 0;
		for (int i = 1;i<array.size();i++) {
			if (array[i] == 0) {
				target1 = i;
				break;
			}
		}
		int distance = 10000;
		for (int i = 1;i < array.size();i++) {
			if (array[i]>1) {
				distance = min(distance,abs(target1-i));
				if (distance == abs(target1 - i)) {
					target2 = i;
				}
			}
		}
		if (target1==0 && target2) {
			break;
		}
		else if (target2 > target1) {
			cost += target2 - target1;
			array[target2]--;
			array[target1]++;
		}
		else if (target2 < target1) {
			cost += target1 - target2;
			array[target2]--;
			array[target1]++;
		}
		for (int i = 1;i<array.size();i++) {
			if (array[i] == 1)flag = true;
			else flag = false;
		}
	}

	cout << cost << endl;
	
	return 0;
}