#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template <typename T> T inverse(T a, T m) {
T u = 0, v = 1;
while (a != 0) {
T t = m / a;
m -= t * a;
swap(a, m);
u -= t * v;
swap(u, v);
}
assert(m == 1);
return u;
}
template <typename T> class Modular {
public:
using Type = typename std::decay<decltype(T::value)>::type;
constexpr Modular() : value() {}
template <typename U> Modular(const U &x) { value = normalize(x); }
template <typename U> static Type normalize(const U &x) {
Type v;
if (-mod() <= x && x < mod())
v = static_cast<Type>(x);
else
v = static_cast<Type>(x % mod());
if (v < 0)
v += mod();
return v;
}
const Type &operator()() const { return value; }
template <typename U> explicit operator U() const {
return static_cast<U>(value);
}
constexpr static Type mod() { return T::value; }
Modular &operator+=(const Modular &other) {
value += other.value;
value -= (value >= mod()) * mod();
return *this;
}
Modular &operator-=(const Modular &other) {
value -= other.value;
value += (value < 0) * mod();
return *this;
}
template <typename U> Modular &operator+=(const U &other) {
return *this += Modular(other);
}
template <typename U> Modular &operator-=(const U &other) {
return *this -= Modular(other);
}
Modular &operator++() { return *this += 1; }
Modular &operator--() { return *this -= 1; }
Modular operator++(int) {
Modular result(*this);
*this += 1;
return result;
}
Modular operator--(int) {
Modular result(*this);
*this -= 1;
return result;
}
Modular operator-() const { return Modular(-value); }
template <typename U = T>
typename std::enable_if<std::is_same<typename Modular<U>::Type, int>::value,
Modular>::type &
operator*=(const Modular &rhs) {
value = normalize(static_cast<int64_t>(value) *
static_cast<int64_t>(rhs.value));
return *this;
}
template <typename U = T>
typename std::enable_if<
std::is_same<typename Modular<U>::Type, int64_t>::value, Modular>::type &
operator*=(const Modular &rhs) {
int64_t q = int64_t(static_cast<long double>(value) * rhs.value / mod());
value = normalize(value * rhs.value - q * mod());
return *this;
}
template <typename U = T>
typename std::enable_if<!std::is_integral<typename Modular<U>::Type>::value,
Modular>::type &
operator*=(const Modular &rhs) {
value = normalize(value * rhs.value);
return *this;
}
Modular &operator/=(const Modular &other) {
return *this *= Modular(inverse(other.value, mod()));
}
friend const Type &abs(const Modular &x) { return x.value; }
template <typename U>
friend bool operator==(const Modular<U> &lhs, const Modular<U> &rhs);
template <typename U>
friend bool operator<(const Modular<U> &lhs, const Modular<U> &rhs);
template <typename V, typename U>
friend V &operator>>(V &stream, Modular<U> &number);
private:
Type value;
};
template <typename T>
bool operator==(const Modular<T> &lhs, const Modular<T> &rhs) {
return lhs.value == rhs.value;
}
template <typename T, typename U>
bool operator==(const Modular<T> &lhs, U rhs) {
return lhs == Modular<T>(rhs);
}
template <typename T, typename U>
bool operator==(U lhs, const Modular<T> &rhs) {
return Modular<T>(lhs) == rhs;
}
template <typename T>
bool operator!=(const Modular<T> &lhs, const Modular<T> &rhs) {
return !(lhs == rhs);
}
template <typename T, typename U>
bool operator!=(const Modular<T> &lhs, U rhs) {
return !(lhs == rhs);
}
template <typename T, typename U>
bool operator!=(U lhs, const Modular<T> &rhs) {
return !(lhs == rhs);
}
template <typename T>
bool operator<(const Modular<T> &lhs, const Modular<T> &rhs) {
return lhs.value < rhs.value;
}
template <typename T>
Modular<T> operator+(const Modular<T> &lhs, const Modular<T> &rhs) {
return Modular<T>(lhs) += rhs;
}
template <typename T, typename U>
Modular<T> operator+(const Modular<T> &lhs, U rhs) {
return Modular<T>(lhs) += rhs;
}
template <typename T, typename U>
Modular<T> operator+(U lhs, const Modular<T> &rhs) {
return Modular<T>(lhs) += rhs;
}
template <typename T>
Modular<T> operator-(const Modular<T> &lhs, const Modular<T> &rhs) {
return Modular<T>(lhs) -= rhs;
}
template <typename T, typename U>
Modular<T> operator-(const Modular<T> &lhs, U rhs) {
return Modular<T>(lhs) -= rhs;
}
template <typename T, typename U>
Modular<T> operator-(U lhs, const Modular<T> &rhs) {
return Modular<T>(lhs) -= rhs;
}
template <typename T>
Modular<T> operator*(const Modular<T> &lhs, const Modular<T> &rhs) {
return Modular<T>(lhs) *= rhs;
}
template <typename T, typename U>
Modular<T> operator*(const Modular<T> &lhs, U rhs) {
return Modular<T>(lhs) *= rhs;
}
template <typename T, typename U>
Modular<T> operator*(U lhs, const Modular<T> &rhs) {
return Modular<T>(lhs) *= rhs;
}
template <typename T>
Modular<T> operator/(const Modular<T> &lhs, const Modular<T> &rhs) {
return Modular<T>(lhs) /= rhs;
}
template <typename T, typename U>
Modular<T> operator/(const Modular<T> &lhs, U rhs) {
return Modular<T>(lhs) /= rhs;
}
template <typename T, typename U>
Modular<T> operator/(U lhs, const Modular<T> &rhs) {
return Modular<T>(lhs) /= rhs;
}
template <typename T, typename U>
Modular<T> power(const Modular<T> &a, const U &b) {
assert(b >= 0);
Modular<T> x = a, res = 1;
U p = b;
while (p > 0) {
if (p & 1)
res *= x;
x *= x;
p >>= 1;
}
return res;
}
template <typename T> bool IsZero(const Modular<T> &number) {
return number() == 0;
}
template <typename T> std::string to_string(const Modular<T> &number) {
return std::to_string(number());
}
// U == std::ostream? but done this way because of fastoutput
template <typename U, typename T>
U &operator<<(U &stream, const Modular<T> &number) {
return stream << number();
}
// U == std::istream? but done this way because of fastinput
template <typename U, typename T> U &operator>>(U &stream, Modular<T> &number) {
typename std::common_type<typename Modular<T>::Type, int64_t>::type x;
stream >> x;
number.value = Modular<T>::normalize(x);
return stream;
}
// constexpr int md = 998244353;
constexpr int md = 1e9 + 7;
using Mint =
Modular<std::integral_constant<std::decay<decltype(md)>::type, md>>;
struct Comb {
int n;
std::vector<Mint> _fac;
std::vector<Mint> _invfac;
std::vector<Mint> _inv;
Comb() : n{0}, _fac{Mint(1)}, _invfac{Mint(1)}, _inv{Mint(0)} {}
Comb(int n_) : Comb() { init(n_); }
void init(int m) {
if (m <= n)
return;
_fac.resize(m + 1);
_invfac.resize(m + 1);
_inv.resize(m + 1);
for (int i = n + 1; i <= m; i++) {
_fac[i] = _fac[i - 1] * i;
}
_invfac[m] = power(_fac[m], md - 2);
for (int i = m; i > n; i--) {
_invfac[i - 1] = _invfac[i] * i;
_inv[i] = _invfac[i] * _fac[i - 1];
}
n = m;
}
Mint fac(int m) {
if (m > n)
init(max(2 * m, m));
return _fac[m];
}
Mint invfac(int m) {
if (m > n)
init(max(2 * m, m));
return _invfac[m];
}
Mint inv(int m) {
if (m > n)
init(max(2 * m, m));
return _inv[m];
}
Mint binom(int nn, int kk) {
if (kk < 0 || kk > nn)
return Mint(0);
if (nn > n)
init(max(2 * nn, nn));
return _fac[nn] * _invfac[kk] * _invfac[nn - kk];
}
} comb;
Mint C(int n, int k) { return comb.binom(n, k); }
Mint fac(int n) { return comb.fac(n); }
Mint Inv(int n) { return comb.inv(n); }
Mint Cat(int n) { return n == 0 ? 1 : C(2 * n, n) / (n + 1); }
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<int> d(n + 1), x(n + 1);
for (int i = 1; i <= n; ++i) {
cin >> d[i] >> x[i];
}
vector<Mint> dp(n + 2);
// dp[i] = 1 + sum(dp[i + d[i]], dp[[i + 2 * dp[i]]] ..., dp[i + x[i] * d[i]])
int B = sqrt(n) + 1;
vector<vector<Mint>> pref(B + 1, vector<Mint>(n + B + 2));
for (int i = n; i; --i) {
dp[i] = 1;
if (d[i]) {
if (d[i] <= B) {
int step = d[i];
int l = i + step;
ll r = 1ll * i + 1ll * (x[i] + 1) * d[i];
if (l <= n) {
dp[i] += pref[step][l];
if (r <= n)
dp[i] -= pref[step][r];
}
} else {
for (ll j = 1ll * i + d[i], cnt = 1; j <= n && cnt <= x[i];
j += d[i], ++cnt)
dp[i] += dp[j];
}
}
for (int step = 1; step <= B; ++step) {
pref[step][i] = dp[i];
if (i + step <= n) {
pref[step][i] += pref[step][i + step];
}
}
}
cout << dp[1];
return 0;
}
