#include<bits/stdc++.h>
#define rep(i, x, y) for(register int i = x; i <= y; ++i)
#define repd(i, x, y) for(register int i = x; i >= y; --i)
#define repl(i, x) for(register int i = fi[x]; i; i = l[i].next)
#define p_b push_back
#define m_p make_pair
#define X first
#define Y second
using namespace std;
typedef long long ll;
const int maxn = 210;
int n, a[maxn];
int read(){
	int num = 0, flag = 1; char c = getchar();
	for(; c < '0' || c > '9'; c = getchar())
		if(c == '-') flag = 0;
	for(; c >= '0' && c <= '9'; c = getchar())
		num = (num<<3)+(num<<1)+c-48;
	return flag? num: -num;
}

void init(){
	n = read();
	rep(i, 1, n*2) a[i] = read();
	sort(a+1, a+n*2+1);
}

void work(){
	ll sum = 0;
	rep(i, 1, n) sum += a[2*i-1];
	printf("%lld\n", sum);
}

int main(){
	//freopen(".in", "r", stdin);
	//freopen(".out", "w", stdout);
	init();
	work();
	return 0;
}