#include <bits/stdc++.h>
using namespace std;

#include <atcoder/all>
using namespace atcoder;

using ll = long long;
using mint = modint998244353;

int main() {
    int N;
    cin >> N;
    ll x, y, z;
    x = y = z = 0;
    while(N--) {
        ll a, b;
        cin >> a >> b;
        if(a % 8 == 0) x += b;
        else if(a % 4 == 0) y += b;
        else if(a % 2 == 0) z += b;
    }
    ll w = min(y, z);
    cout << (x + w + (y - w) / 2 + (z - w) / 3) << endl;
}