/*
  ID: mytbk921
  LANG: C
  TASK: skidesign
*/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int compare(const void *a, const void *b)
{
	return *(int*)a - *(int*)b;
}

int calc_sum(int min, int N, int a[])
{
	int sum = 0;
	int i;

	for (i = 0; i < N && a[i] < min; i++) {
		int diff = min - a[i];
		sum += diff * diff;
	}

	for (i = N-1; i >= 0 && a[i] - min > 17; i--) {
		int diff = a[i] - min - 17;
		sum += diff * diff;
	}
	return sum;
}

int main()
{
	FILE *fin, *fout;
	int N;
	int m[1000];
	int sum, ans;
	int i;

	fin = fopen("skidesign.in", "r");
	fout = fopen("skidesign.out", "w");

	fscanf(fin, "%d", &N);
	for (i = 0; i<N; i++)
		fscanf(fin, "%d", &m[i]);
	fclose(fin);
	qsort(m, N, sizeof(int), compare);

	ans = calc_sum(m[0], N, m);
	for (i = m[N-1]; i > 0; i--) {
		sum = calc_sum(m[0]+i, N, m);
		if (sum < ans)
			ans = sum;
	}

	fprintf(fout, "%d\n", ans);
	fclose(fout);
	return 0;
}