#include <stdio.h>

int main()
{
	int l[10001] = {0}, N, i;
	double length = 0;

	scanf("%d", &N);
	for (int j = 0; j < N; j++) {
		scanf("%d", &i);
		l[i]++;                 /* record counts */
	}

	for (i = 0; i < 10001; i++)  /* find the shortest, special case */
		if (l[i]) {
			length = i;
			break;
		}

	for (; i < 10001; i++)       /* make new ropes */
		while (l[i]--)
			length = (length + i) / 2;

	printf("%d", (int)length);

	return 0;
}