#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstdio>

using namespace std;

typedef long long LL;

const int N = 64;

struct Node
{
	int val;
	LL id;
	bool operator<(const Node &t) const
	{
		return val < t.val;
	}
}a[1010];
int d[N];
int n;

bool insert(LL x)
{
	for (int i = 63; i >= 0; i -- )
	{
		if (x >> i & 1)
		{
			if (d[i]) x ^= d[i];
			else
			{
				d[i] = x;
				return true;
			}
		}
	}
	return false;
}

int main()
{
	int res = 0;
	scanf("%d", &n);
	for (int i = 0; i < n; i ++ )
	{
		cin >> a[i].id >> a[i].val;
	}
	sort(a, a + n);
	reverse(a, a + n);
	for (int i = 0; i < n; i ++ )
	{
		if (insert(a[i].id)) res += a[i].val;
	}
	cout << res << endl;
	return 0;
}