#include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"
//!===========================================================!//
//!  dP     dP                          dP                    !//
//!  88     88                          88                    !//
//!  88aaaaa88a .d8888b. .d8888b. .d888b88 .d8888b. 88d888b.  !//
//!  88     88  88ooood8 88'  '88 88'  '88 88ooood8 88'  '88  !//
//!  88     88  88.  ... 88.  .88 88.  .88 88.  ... 88        !//
//!  dP     dP  '88888P' '88888P8 '88888P8 '88888P' dP        !//
//!===========================================================!//
#ifndef HOGEPACHI_ASSERT
#define NDEBUG
#endif
using ld = long double;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
template <typename T>
constexpr T INF = std::numeric_limits<T>::max() / 4;
template <typename T>
constexpr T MOD = static_cast<T>(1000000007);
template <typename F>
constexpr F PI = static_cast<F>(3.1415926535897932385);
//! メルセンヌ・ツイスタ !//
std::mt19937 mt{std::random_device{}()};
//! Debug出力 !//
#define SHOW(...) (std::cerr << "(" << #__VA_ARGS__ << ") = ("), HogeHogeSansuu(__VA_ARGS__), std::cerr << ")" << std::endl
struct has_debugPrint_impl
{
    template <class T>
    static auto check(T&& x) -> decltype(x.debugPrint(), std::true_type{});
    template <class T>
    static auto check(...) -> std::false_type;
};
template <class T>
class has_debugPrint : public decltype(has_debugPrint_impl::check<T>(std::declval<T>()))
{
};
template <bool>
struct HogeHogeDump
{
    template <typename T>
    static void dump(const T& x) { x.debugPrint(); }
};
template <>
struct HogeHogeDump<false>
{
    template <typename T>
    static void dump(const T& x) { std::cerr << x; }
};
void HogeHogeSansuu() { ; }
template <typename T>
void HogeHogeSansuu(const T& x) { HogeHogeDump<has_debugPrint<T>::value>::dump(x); }
template <typename T, typename... Args>
void HogeHogeSansuu(const T& x, Args... args) { HogeHogeDump<has_debugPrint<T>::value>::dump(x), std::cerr << ",", HogeHogeSansuu(args...); }
//! chminとchmax !//
template <typename T>
bool chmin(T& a, const T& b) { return a = std::min(a, b), a == b; }
template <typename T>
bool chmax(T& a, const T& b) { return a = std::max(a, b), a == b; }
//! Rep関数 !//
template <typename T, typename F>
void For(const T s, const T t, const F f)
{
    for (T i = s; i != t; i += T(s < t ? 1 : -1)) { f(i); }
}
template <typename T, typename F>
void Rep(const T N, const F f) { For<T, F>(0, N, f); }
template <typename T, typename F>
void RRep(const T N, const F f) { For<T, F>(N - 1, -1, f); }
//! Vec関数 !//
template <typename T>
std::vector<T> Vec(const std::size_t n, T v) { return std::vector<T>(n, v); }
template <class... Args>
auto Vec(const std::size_t n, Args... args) { return std::vector<decltype(Vec(args...))>(n, Vec(args...)); }
//! ビット演算 !//
template <typename T>
constexpr T popCount(const T u)
{
#ifdef __has_builtin
    return u == 0 ? T(0) : (T)__builtin_popcountll(u);
#else
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = (v & 0x5555555555555555ULL) + (v >> 1 & 0x5555555555555555ULL), v = (v & 0x3333333333333333ULL) + (v >> 2 & 0x3333333333333333ULL), v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL, static_cast<T>(v * 0x0101010101010101ULL >> 56 & 0x7f);
#endif
}
template <typename T>
constexpr T log2p1(const T u)
{
#ifdef __has_builtin
    return u == 0 ? T(0) : T(64 - __builtin_clzll(u));
#else
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = static_cast<unsigned long long>(v), v |= (v >> 1), v |= (v >> 2), v |= (v >> 4), v |= (v >> 8), v |= (v >> 16), v |= (v >> 32), popCount(v);
#endif
}
template <typename T>
constexpr T clog(const T v) { return v == 0 ? T(0) : log2p1(v - 1); }
template <typename T>
constexpr T msbp1(const T v) { return log2p1(v); }
template <typename T>
constexpr T lsbp1(const T v)
{
#ifdef __has_builtin
    return __builtin_ffsll(v);
#else
    return v == 0 ? T(0) : popCount((v & (-v)) - T(1)) + T(1);
#endif
}
template <typename T>
constexpr bool ispow2(const T v) { return popCount(v) == 1; }
template <typename T>
constexpr T ceil2(const T v) { return v == 0 ? T(1) : T(1) << log2p1(v - 1); }
template <typename T>
constexpr T floor2(const T v) { return v == 0 ? T(0) : T(1) << (log2p1(v) - 1); }
//! 累積和 !//
template <typename T>
struct Accum
{
    template <typename InIt>
    Accum(const InIt first, const InIt last) : accum(std::size_t(std::distance(first, last))) { std::partial_sum(first, last, accum.begin()); }
    T sum(const std::size_t i) const { return i == 0 ? T(0) : accum[i - 1]; }
    T sum(const std::size_t l, const std::size_t r) const { return sum(r) - sum(l); }
    std::vector<T> accum;
};
template <typename T>
struct Accum2D
{
    Accum2D(const std::vector<std::vector<T>>& t) : accum{t}
    {
        for (std::size_t i = 0; i < accum.size(); i++) {
            for (std::size_t j = 1; j < accum[i].size(); j++) { accum[i][j] += accum[i][j - 1]; }
        }
        for (std::size_t i = 1; i < accum.size(); i++) {
            for (std::size_t j = 0; j < accum[i].size(); j++) { accum[i][j] += accum[i - 1][j]; }
        }
    }
    T sum(const std::size_t y, const std::size_t x) const { return y == 0 or x == 0 ? T(0) : accum[y - 1][x - 1]; }
    T sum(const std::size_t ymin, const std::size_t ysup, const std::size_t xmin, const std::size_t xsup) const { return sum(ysup, xsup) - sum(ymin, xmin); }
    std::vector<std::vector<T>> accum;
};
//! 座標圧縮 !//
template <typename T>
struct Zip
{
    template <typename InIt>
    Zip(const InIt first, const InIt last) : unzip(std::size_t(std::distance(first, last)))
    {
        std::copy(first, last, unzip), std::sort(unzip.begin(), unzip.end()), unzip.erase(std::unique(unzip.begin(), unzip.end()), unzip.end());
        for (std::size_t i = 0; i < unzip.size(); i++) { zip[unzip[i]] = i; }
    }
    std::vector<T> unzip;
    std::map<T, std::size_t> zip;
};
//! STLの出力関数 !//
template <typename T, std::size_t N>
std::ostream& operator<<(std::ostream& os, const std::array<T, N>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename T, typename A>
std::ostream& operator<<(std::ostream& os, const std::deque<T, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename K, typename T, typename C, typename A>
std::ostream& operator<<(std::ostream& os, const std::multimap<K, T, C, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << "<" << e.first << ": " << e.second << ">,"; }
    return (os << "]" << std::endl);
}
template <typename T, typename C, typename A>
std::ostream& operator<<(std::ostream& os, const std::multiset<T, C, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename K, typename T, typename C, typename A>
std::ostream& operator<<(std::ostream& os, const std::map<K, T, C, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << "<" << e.first << ": " << e.second << ">,"; }
    return (os << "]" << std::endl);
}
template <typename T1, typename T2>
std::ostream& operator<<(std::ostream& os, const std::pair<T1, T2>& v) { return (os << "<" << v.first << "," << v.second << ">"); }
template <typename T1, typename T2, typename T3>
std::ostream& operator<<(std::ostream& os, const std::priority_queue<T1, T2, T3>& v)
{
    auto q = v;
    os << "[";
    while (not q.empty()) { os << q.top() << ",", q.pop(); }
    return os << "]\n";
}
template <typename T1, typename T2>
std::ostream& operator<<(std::ostream& os, const std::queue<T1>& v)
{
    auto q = v;
    os << "[";
    while (not q.empty()) { os << q.front() << ",", q.pop(); }
    return os << "]\n";
}
template <typename T, typename C, typename A>
std::ostream& operator<<(std::ostream& os, const std::set<T, C, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename T1, typename T2>
std::ostream& operator<<(std::ostream& os, const std::stack<T1>& v)
{
    auto q = v;
    os << "[";
    while (not q.empty()) { os << q.top() << ",", q.pop(); }
    return os << "]\n";
}
template <typename K, typename T, typename H, typename P, typename A>
std::ostream& operator<<(std::ostream& os, const std::unordered_multimap<K, T, H, P, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << "<" << e.first << ": " << e.second << ">,"; }
    return (os << "]" << std::endl);
}
template <typename T, typename H, typename P, typename A>
std::ostream& operator<<(std::ostream& os, const std::unordered_multiset<T, H, P, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename K, typename T, typename H, typename P, typename A>
std::ostream& operator<<(std::ostream& os, const std::unordered_map<K, T, H, P, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << "<" << e.first << ": " << e.second << ">,"; }
    return (os << "]" << std::endl);
}
template <typename T, typename H, typename P, typename A>
std::ostream& operator<<(std::ostream& os, const std::unordered_set<T, H, P, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename T, typename A>
std::ostream& operator<<(std::ostream& os, const std::vector<T, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
//!===============================================================!//
//!   88888888b            dP       .88888.   a88888b. 888888ba   !//
//!   88                   88      d8'   '88 d8'   '88 88    '8b  !//
//!  a88aaaa    dP.  .dP d8888P    88        88        88     88  !//
//!   88         '8bd8'    88      88   YP88 88        88     88  !//
//!   88         .d88b.    88      Y8.   .88 Y8.   .88 88    .8P  !//
//!   88888888P dP'  'dP   dP       '88888'   Y88888P' 8888888P   !//
//!===============================================================!//
template <typename T>
constexpr std::pair<T, T> extgcd(const T a, const T b)
{
    if (b == 0) { return std::pair<T, T>{1, 0}; }
    const auto p = extgcd(b, a % b);
    return {p.second, p.first - p.second * (a / b)};
}
template <typename T>
constexpr T inverse(const T a, const T mod) { return (mod + extgcd((mod + a % mod) % mod, mod).first % mod) % mod; }
//!========================================================!//
//!  8888ba.88ba                 dP    dP            dP    !//
//!  88  '8b  '8b                88    88            88    !//
//!  88   88   88 .d8888b. .d888b88    88 88d888b. d8888P  !//
//!  88   88   88 88'  '88 88'  '88    88 88'  '88   88    !//
//!  88   88   88 88.  .88 88.  .88    88 88    88   88    !//
//!  dP   dP   dP '88888P' '88888P8    dP dP    dP   dP    !//
//!========================================================!//
template <uint mod>
class ModInt
{
private:
    uint v;
    static uint norm(const uint& x) { return x < mod ? x : x - mod; }
    static ModInt make(const uint& x)
    {
        ModInt m;
        return m.v = x, m;
    }
    static ModInt power(ModInt x, ll n)
    {
        ModInt ans = 1;
        for (; n; n >>= 1, x *= x) {
            if (n & 1) { ans *= x; }
        }
        return ans;
    }
    static ModInt inv(const ModInt& x) { return ModInt{inverse((ll)x.v, (ll)mod)}; }

public:
    ModInt() : v{0} {}
    ModInt(const ll val) : v{norm(uint(val % (ll)mod + (ll)mod))} {}
    ModInt(const ModInt<mod>& n) : v{n()} {}
    explicit operator bool() const { return v != 0; }
    ModInt<mod>& operator=(const ModInt<mod>& n) { return v = n(), (*this); }
    ModInt<mod>& operator=(const ll val) { return v = norm(uint(val % (ll)mod + (ll)mod)), (*this); }
    ModInt<mod> operator+() const { return *this; }
    ModInt<mod> operator-() const { return make(norm(mod - v)); }
    ModInt<mod> operator+(const ModInt<mod>& val) const { return make(norm(v + val())); }
    ModInt<mod> operator-(const ModInt<mod>& val) const { return make(norm(v + mod - val())); }
    ModInt<mod> operator*(const ModInt<mod>& val) const { return make((uint)((ll)v * val() % (ll)mod)); }
    ModInt<mod> operator/(const ModInt<mod>& val) const { return *this * inv(val()); }
    ModInt<mod>& operator+=(const ModInt<mod>& val) { return *this = *this + val; }
    ModInt<mod>& operator-=(const ModInt<mod>& val) { return *this = *this - val; }
    ModInt<mod>& operator*=(const ModInt<mod>& val) { return *this = *this * val; }
    ModInt<mod>& operator/=(const ModInt<mod>& val) { return *this = *this / val; }
    ModInt<mod> operator+(const ll val) const { return ModInt{v + val}; }
    ModInt<mod> operator-(const ll val) const { return ModInt{v - val}; }
    ModInt<mod> operator*(const ll val) const { return ModInt{(ll)v * (val % mod)}; }
    ModInt<mod> operator/(const ll val) const { return ModInt{(ll)v * inv(val)}; }
    template <typename I>
    ModInt<mod> operator^(const I n) const { return power(v, n); }
    ModInt<mod>& operator+=(const ll val) { return *this = *this + val; }
    ModInt<mod>& operator-=(const ll val) { return *this = *this - val; }
    ModInt<mod>& operator*=(const ll val) { return *this = *this * val; }
    ModInt<mod>& operator/=(const ll val) { return *this = *this / val; }
    template <typename I>
    ModInt<mod>& operator^=(const I n) { return (*this) = ((*this) ^ n); }
    bool operator==(const ModInt<mod>& val) const { return v == val.v; }
    bool operator!=(const ModInt<mod>& val) const { return not(*this == val); }
    bool operator==(const ll val) const { return v == norm(uint((ll)mod + val % (ll)mod)); }
    bool operator!=(const ll val) const { return not(*this == val); }
    uint operator()() const { return v; }
};
template <uint mod>
inline ModInt<mod> operator+(const ll val, const ModInt<mod>& n) { return n + val; }
template <uint mod>
inline ModInt<mod> operator-(const ll val, const ModInt<mod>& n) { return ModInt<mod>{val - (ll)n()}; }
template <uint mod>
inline ModInt<mod> operator*(const ll val, const ModInt<mod>& n) { return n * val; }
template <uint mod>
inline ModInt<mod> operator/(const ll val, const ModInt<mod>& n) { return ModInt<mod>(val) / n; }
template <uint mod>
inline bool operator==(const ll val, const ModInt<mod>& n) { return n == val; }
template <uint mod>
inline bool operator!=(const ll val, const ModInt<mod>& n) { return not(val == n); }
template <uint mod>
inline std::istream& operator>>(std::istream& is, ModInt<mod>& n)
{
    uint v;
    return is >> v, n = v, is;
}
template <uint mod>
std::ostream& operator<<(std::ostream& os, const ModInt<mod>& n) { return (os << n()); }
//!============================================================================!//
//!  8888ba.88ba                 dP     a88888b.                     dP        !//
//!  88  '8b  '8b                88    d8'   '88                     88        !//
//!  88   88   88 .d8888b. .d888b88    88        .d8888b. 88d8b.d8b. 88d888b.  !//
//!  88   88   88 88'  '88 88'  '88    88        88'  '88 88''88''88 88'  '88  !//
//!  88   88   88 88.  .88 88.  .88    Y8.   .88 88.  .88 88  88  88 88.  .88  !//
//!  dP   dP   dP '88888P' '88888P8     Y88888P' '88888P' dP  dP  dP 88Y8888'  !//
//!============================================================================!//
template <uint mod>
class ModComb
{
public:
    ModComb(const std::size_t N) : f(N + 1, ModInt<mod>(1)), in(N + 1, ModInt<mod>(1)), invf(N + 1, ModInt<mod>(1))
    {
        for (uint i = 2; i <= N; i++) { f[i] = f[i - 1] * i, in[i] = (mod - (mod / i)) * in[mod % i], invf[i] = invf[i - 1] * in[i]; }
    }
    ModInt<mod> fact(const std::size_t N) const { return f[N]; }
    ModInt<mod> inv(const std::size_t N) const { return in[N]; }
    ModInt<mod> invFact(const std::size_t N) const { return invf[N]; }
    ModInt<mod> perm(const std::size_t N, const std::size_t K) const { return f[N] * invf[N - K]; }
    ModInt<mod> comb(const std::size_t N, const std::size_t K) const { return f[N] * invf[K] * invf[N - K]; }

private:
    std::vector<ModInt<mod>> f, in, invf;
};
//!============================================!//
//!    8888ba.88ba             oo              !//
//!    88  '8b  '8b                            !//
//!    88   88   88  .d8888b.  dP  88d888b.    !//
//!    88   88   88  88'  '88  88  88'  '88    !//
//!    88   88   88  88.  .88  88  88    88    !//
//!    dP   dP   dP  '88888P8  dP  dP    dP    !//
//!============================================!//
constexpr int M = 2000;
using mll = ModInt<MOD<uint>>;
mll dp[2 * M + 1][2 * M + 1];
ModComb<MOD<uint>> modcomb(4 * M);
int main()
{
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    int N;
    std::cin >> N;
    std::vector<int> A(N), B(N);
    for (int i = 0; i < N; i++) { std::cin >> A[i] >> B[i], dp[M - A[i]][M - B[i]] += 1; }
    for (int y = -M; y <= M; y++) {
        for (int x = -M; x <= M; x++) {
            constexpr int D[] = {1, 0, 1};
            for (int d = 0; d < 2; d++) {
                const int ny = y + D[d], nx = x + D[d + 1];
                if (ny <= M and nx <= M) { dp[M + ny][M + nx] += dp[M + y][M + x]; }
            }
        }
    }
    mll ans = 0;
    for (int i = 0; i < N; i++) { ans += dp[M + A[i]][M + B[i]] - modcomb.comb(2 * A[i] + 2 * B[i], 2 * A[i]); }
    std::cout << ans / 2 << std::endl;
    return 0;
}


Measured memory_bytes: 64512