#line 1 "test\\yukicoder\\448.test.cpp"
#include <algorithm>
#define PROBLEM "https://yukicoder.me/problems/448"

#line 1 "lib\\math\\crt_mod.hpp"



#line 1 "lib\\util.hpp"



#include <cassert>
#include <cstddef>
#include <cstdint>
#include <type_traits>

namespace tifa_libs {

using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
using i128 = __int128_t;
using u128 = __uint128_t;

}  // namespace tifa_libs


#line 5 "lib\\math\\crt_mod.hpp"

#line 1 "lib\\math\\inverse.hpp"



#line 5 "lib\\math\\inverse.hpp"

#line 1 "lib\\math\\inv_gcd.hpp"



#line 5 "lib\\math\\inv_gcd.hpp"

#line 1 "lib\\math\\exgcd.hpp"



#line 5 "lib\\math\\exgcd.hpp"

#include <tuple>

namespace tifa_libs::math {

// @return tuple(g, x, y) s.t. g = gcd(a, b), xa + yb = g, |x| + |y| is the minimal (primary) and x <= y (secondarily)
constexpr std::tuple<u64, i64, i64> exgcd(i64 a, i64 b) {
  i64 x1 = 1, x2 = 0, x3 = 0, x4 = 1;
  while (b) {
    i64 c = a / b;
    std::tie(x1, x2, x3, x4, a, b) = std::make_tuple(x3, x4, x1 - x3 * c, x2 - x4 * c, b, a - b * c);
  }
  return {a, x1, x2};
}

}  // namespace tifa_libs::math


#line 7 "lib\\math\\inv_gcd.hpp"

namespace tifa_libs::math {

constexpr std::pair<u64, u64> inv_gcd(u64 n, u64 mod) {
  auto [g, x, y] = exgcd((i64)(n % mod), (i64)mod);
  return {g, x > 0 ? (u64)x : (u64)(x % (i64)mod + (i64)mod) % mod};
}

}  // namespace tifa_libs::math


#line 7 "lib\\math\\inverse.hpp"

namespace tifa_libs::math {

constexpr u64 inverse(u64 n, u64 mod) {
  auto [g, x] = inv_gcd(n % mod, mod);
  assert(g == 1);
  return x;
}

}  // namespace tifa_libs::math


#line 1 "lib\\math\\safe_mod.hpp"



#line 5 "lib\\math\\safe_mod.hpp"

namespace tifa_libs::math {

template <class T, std::enable_if_t<std::is_signed_v<T>, int> = 0>
constexpr T safe_mod(T x, std::make_unsigned_t<T> mod) { return ((x %= (T)mod) < 0 ? x + (T)mod : x); }

}  // namespace tifa_libs::math


#line 8 "lib\\math\\crt_mod.hpp"

#include <numeric>
#include <optional>
#include <vector>

namespace tifa_libs::math {

inline std::optional<std::pair<u32, u32>> crt_mod(const std::vector<i32> &a, const std::vector<u32> &m, const u32 mod) {
  assert(a.size() == m.size());
  const size_t n = a.size();
  std::vector<u32> m_cpy(m);
  for (size_t i = 0; i < n; ++i) {
    u32 &mi = m_cpy[i];
    for (size_t j = 0; j < i; ++j) {
      u32 &mj = m_cpy[j], d = std::gcd(mi, mj);
      if (d == 1) continue;
      if (safe_mod(a[i], d) != safe_mod(a[j], d)) return {};
      mi /= d;
      mj /= d;
      if (u32 k = std::gcd(mi, d); k != 1)
        while (d % k == 0) {
          mi *= k;
          d /= k;
        }
      mj *= d;
    }
  }
  m_cpy.push_back(mod);
  std::vector<i32> pp(n + 1, 1), res(n + 1);
  for (size_t i = 0; i < n; ++i) {
    i64 u = safe_mod((safe_mod(a[i], m_cpy[i]) - res[i]) * (i64)inverse((u64)pp[i], m_cpy[i]), m_cpy[i]);
    for (size_t j = i + 1; j <= n; ++j) {
      res[j] = (i32)((res[j] + u * pp[j]) % m_cpy[j]);
      pp[j] = (i32)((i64)pp[j] * m_cpy[i] % m_cpy[j]);
    }
  }
  return std::make_pair(res.back(), pp.back());
}

}  // namespace tifa_libs::math


#line 5 "test\\yukicoder\\448.test.cpp"

#include <iostream>
#line 8 "test\\yukicoder\\448.test.cpp"

int main() {
  size_t n;
  std::cin >> n;
  std::vector<tifa_libs::i32> r(n);
  std::vector<tifa_libs::u32> m(n);
  for (size_t i = 0; i < n; ++i) std::cin >> r[i] >> m[i];
  auto res = tifa_libs::math::crt_mod(r, m, 1'000'000'007);
  if (!res) {
    std::cout << "-1\n";
    return 0;
  }
  std::cout << ((size_t)std::count(r.begin(), r.end(), 0) == n ? res->second : res->first) << '\n';
  return 0;
}