#include <bits/stdc++.h>
#pragma warning(disable : 4996)
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("-ffloat-store")
using namespace std;
clock_t time_p = clock();
void aryanc403() {
  time_p = clock() - time_p;
  cerr << "Time Taken : " << (float)(time_p) / CLOCKS_PER_SEC << "\n";
}
const long long int INF = 0xFFFFFFFFFFFFFFFL;
long long int seed;
mt19937 rng(seed = chrono::steady_clock::now().time_since_epoch().count());
inline long long int rnd(long long int l = 0, long long int r = INF) {
  return uniform_int_distribution<long long int>(l, r)(rng);
}
class CMP {
 public:
  bool operator()(pair<long long int, long long int> a,
                  pair<long long int, long long int> b) {
    return !(a.first < b.first || a.first == b.first && a.second <= b.second);
  }
};
void add(map<long long int, long long int> &m, long long int x,
         long long int cnt = 1) {
  auto jt = m.find(x);
  if (jt == m.end())
    m.insert({x, cnt});
  else
    jt->second += cnt;
}
void del(map<long long int, long long int> &m, long long int x,
         long long int cnt = 1) {
  auto jt = m.find(x);
  if (jt->second <= cnt)
    m.erase(jt);
  else
    jt->second -= cnt;
}
bool cmp(const pair<long long int, long long int> &a,
         const pair<long long int, long long int> &b) {
  return a.first < b.first || (a.first == b.first && a.second < b.second);
}
const long long int mod = 1000000007L;
const long long int logN = 61;
long long int T, n, i, j, k, in, cnt, l, r, u, v, x, y;
long long int m, ans, sum, sum2;
string s;
vector<pair<long long int, long long int> > a[logN + 5], b;
long long int hgh(long long int x) {
  long long int i;
  for (i = (0); i <= (logN); ++i)
    if (x & (1LL << i)) return i;
  assert(false);
}
long long int sgn(long long int x) {
  if (x == 0) return 0;
  return x / abs(x);
}
int main(void) {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  {
    cin >> n;
    for (i = 0; i < (n); ++i) {
      cin >> x >> y;
      a[hgh(y)].push_back({x, y});
      sum += x;
    }
    for (i = (logN); i >= (0); --i) {
      long long int cnt = 0;
      for (auto x : a[i]) {
        if (__builtin_popcountll(x.second & ans) & 1)
          cnt -= x.first;
        else
          cnt += x.first;
      }
      if (sgn(sum) * sgn(cnt) > 0) {
        ;
        ans |= (1LL << i);
      }
    }
    cout << ans << "\n";
  }
  aryanc403();
  return 0;
}
