#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
	vector<int*> pyramid_blocks;
	int index = 0;
	for (int count_block = 1; count_block < 10000; count_block += 2) {
		int *blocks = new int[2];
		if (count_block == 1) {
			blocks[0] = 1;
			blocks[1] = 1;
		}
		else {
			blocks[0] = pyramid_blocks[index - 1][0] + count_block;
			blocks[1] = count_block;
		}
		pyramid_blocks.push_back(blocks);
		index++;
	}

	int n;
	cin >> n;

	int blocks[101];
	int count_all_block = 0;
	for (int i = 0; i < n; i++) {
		string count_block;
		cin >> count_block;
		blocks[i] = stoi(count_block);
		count_all_block += blocks[i];
	}

	int pyramid_row_index = 0;
	for (int i = 0; i < pyramid_blocks.size(); i++) {
		if (pyramid_blocks[i][0] <= count_all_block) {
			pyramid_row_index = i;
		}
		else {
			break;
		}
	}

	int max_width = pyramid_blocks[pyramid_row_index][1];
	int* pyramid_data = new int[max_width];
	for (int i = 0; i < max_width; i++) {
		pyramid_data[i] = 0;
	}

	int count_row = 0;
	for (int y = pyramid_row_index; y >= 0; y--) {
		int* blocks = pyramid_blocks[y];
		for (int x = 0; x < blocks[1]; x++) {
			pyramid_data[x + count_row]++;
		}
		count_row++;
	}

	for (int i = 0; i < min(max_width, n); i++) {
		count_all_block -= min(pyramid_data[i], blocks[i]);
	}

	cout << count_all_block << endl;

	return 0;
}