#include <bits/stdc++.h>   using namespace std;   using namespace std;   template <typename T, typename U>   std::istream& operator>>(std::istream& i, pair<T, U>& p) {     i >> p.first >> p.second;     return i;   }   template <typename T>   std::istream& operator>>(std::istream& i, vector<T>& t) {     for (auto& v : t) {       i >> v;     }     return i;   }   template <typename T, typename U>   std::ostream& operator<<(std::ostream& o, const pair<T, U>& p) {     o << p.first <<     << p.second;     return o;   }   template <typename T>   std::ostream& operator<<(std::ostream& o, const vector<T>& t) {     if (t.empty()) o <<   n ;     for (size_t i = 0; i < t.size(); ++i) {       o << t[i] <<    n [i == t.size() - 1];     }     return o;   }   template <typename T>   using minheap = priority_queue<T, vector<T>, greater<T>>;   template <typename T>   using maxheap = priority_queue<T, vector<T>, less<T>>;   template <typename T>   bool in(T a, T b, T c) {     return a <= b && b < c;   }   unsigned int logceil(int x) {     return (unsigned int)(8 * sizeof(int) - __builtin_clz(x));   }   namespace std {   template <typename T, typename U>   struct hash<pair<T, U>> {     hash<T> t;     hash<U> u;     size_t operator()(const pair<T, U>& p) const {       return t(p.x) ^ (u(p.y) << 7);     }   };   }  // namespace std   template <typename T>   T gcd(T a, T b) {     if (a < b) swap(a, b);     return b ? gcd(b, a % b) : a;   }   template <typename T>   class vector2 : public vector<vector<T>> {    public:     vector2() {}     vector2(size_t a, size_t b, T t = T())         : vector<vector<T>>(a, vector<T>(b, t)) {}   };   template <typename T>   class vector3 : public vector<vector2<T>> {    public:     vector3() {}     vector3(size_t a, size_t b, size_t c, T t = T())         : vector<vector2<T>>(a, vector2<T>(b, c, t)) {}   };   template <typename T>   class vector4 : public vector<vector3<T>> {    public:     vector4() {}     vector4(size_t a, size_t b, size_t c, size_t d, T t = T())         : vector<vector3<T>>(a, vector3<T>(b, c, d, t)) {}   };   template <typename T>   class vector5 : public vector<vector4<T>> {    public:     vector5() {}     vector5(size_t a, size_t b, size_t c, size_t d, size_t e, T t = T())         : vector<vector4<T>>(a, vector4<T>(b, c, d, e, t)) {}   };   void fastIO() { ios::sync_with_stdio(false); }   template <typename T, typename... Args>   T max(T t, Args... args) {     return max(max<T>(args...), t);   }   template <typename T, typename... Args>   T min(T t, Args... args) {     return min(min<T>(args...), t);   }   using PLL = pair<long long, unsigned long long>;   class FFooFighters {    public:     void solve(std::istream& in, std::ostream& out) {       fastIO();       int n;       in >> n;       vector<PLL> a(n);       in >> a;       unsigned long long mb = 1;       unsigned long long res = 0;       long long ds = 0;       for (auto p : a) {         ds += p.first;       }       for (int i = 0; i < 64; ++i) {         long long cs = 0;         for (auto p : a) {           if (p.second >= mb && p.second < 2 * mb) {             ds += p.first;             long long nmask = p.second & res;             if (__builtin_popcountll(nmask) % 2 == 1)               cs -= p.first;             else               cs += p.first;           }         }         if (cs != 0 && signbit(ds) == signbit(cs)) {           res |= mb;         }         mb <<= 1;       }       out << res << endl;     }   };   int main() {     FFooFighters solver;     std::istream& in(std::cin);     std::ostream& out(std::cout);     solver.solve(in, out);     return 0;   }