#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define all(x) begin(x), end(x)

template <class T> bool chmin(T& x, T y) {
	return x > y ? (x = y, true) : false;
}
template <class T> bool chmax(T& x, T y) {
	return x < y ? (x = y, true) : false;
}

struct io_setup {
	io_setup() {
		ios::sync_with_stdio(false);
		cin.tie(nullptr);
		cout << fixed << setprecision(15);
	}
} io_setup;

using mint = atcoder::modint998244353;

void solve() {
	int n;
	cin >> n;
	vector<int> a(n), b(n);
	rep(i, 0, n) cin >> a[i] >> b[i];
	vector<ll> sm(3, 0);
	rep(i, 0, n) {
		if (a[i] % 8 == 0) sm[0] += b[i];
		else if (a[i] % 4 == 0) sm[1] += b[i];
		else if (a[i] % 2 == 0) sm[2] += b[i];
	}
	ll ans = 0;
	{
		ll tmp = min(sm[1], sm[2]);
		ans += tmp;
		sm[1] -= tmp;
		sm[2] -= tmp;
	}
	ans += sm[0];
	ans += sm[1] / 2;
	ans += sm[2] / 3;
	cout << ans << "\n";
}

int main() {
	int t = 1;
	// cin >> t;
	while (t--) solve();
}