#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n;
  cin >> n;
  ll t1 = 0, t2 = 0, t3 = 0;
  rep(i, n) {
    ll a, b;
    cin >> a >> b;
    int cnt = 0;
    while (a % 2 == 0) a /= 2, ++cnt;
    if (cnt == 1) t1 += b;
    if (cnt == 2) t2 += b;
    if (cnt >= 3) t3 += b;
  }
  ll ans = t3;
  {
    ll t = min(t1, t2);
    ans += t, t1 -= t, t2 -= t;
  }
  ans += t1 / 3, t1 %= 3;
  ans += t2 / 2, t2 %= 2;
  cout << ans << '\n';
  return 0;
}