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#include <cstdio>
#include <algorithm>

const int MAXN = 2010;

int a[11010101];

int main() {
	// freopen("input.txt", "r", stdin);
	int n;
	scanf("%d", &n);
	int m = n * (n + 1);
	m /= 2;
	for (int i = 0; i < m; i++)
		scanf("%d", &a[i]);
	std::sort(a, a + m);
	long long ans = 0ll;
	for (int i = 0; i < n; i++)
		ans += a[i];
	printf("%lld\n", ans);
	return 0;
}