#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
using namespace std;
using ll = long long;
const int N = 100'000 + 10;
const int MOD = 1'000'000'000 + 7;
template <int Module>
class Mint {
private:
int val;
public:
Mint() : val(0) {};
Mint(ll _val) {
val = _val % Module;
normalization_effect();
}
public:
void normalization_effect() {
/// [- Module, 2 * Module)
this->val = this->val + (this->val < 0) * Module - (this->val >= Module) * Module;
}
int get_val() const { return this->val; }
Mint operator-() const { return Mint(-this->val); }
Mint pw(ll exp) const {
Mint res = 1;
Mint base = *this;
while (exp > 0) {
if(exp & 1ll) res *= base;
base *= base;
exp >>= 1ll;
}
return res;
}
Mint inv() const {
/// Module is prime
/// return 〖val〗^(-1)
return this->pw(Module - 2);
}
public:
Mint& operator+=(const Mint& other) {
this->val += other.val;
this->normalization_effect();
return *this;
}
Mint& operator-=(const Mint& other) {
this->val -= other.val;
this->normalization_effect();
return *this;
}
Mint& operator*=(const Mint& other) {
this->val = 1ll * this->val * other.val % Module;
this->normalization_effect();
return *this;
}
Mint& operator/=(const Mint& other) {
this->operator*=(other.inv());
return *this;
}
Mint& operator++() { this->operator+=(1); return *this; }
Mint& operator--() { this->operator-=(1); return *this; }
Mint operator+(const Mint& other) const {
Mint res = *this;
res += other;
return res;
}
Mint operator-(const Mint& other) const {
Mint res = *this;
res -= other;
return res;
}
Mint operator*(const Mint& other) const {
Mint res = *this;
res *= other;
return res;
}
Mint operator/(const Mint& other) const {
Mint res = *this;
res /= other;
return res;
}
bool operator==(const Mint& other) const {
return (this->val == other.val);
}
public:
friend ostream& operator<<(ostream& os, const Mint& other) {
return os << other.val;
}
};
using mint = Mint<MOD>;
struct event {
int idx, dist, mod, type;
event() : idx(0), dist(0), mod(0), type(0) {};
event(int _idx, int _dist, int _mod, int _type) : idx(_idx), dist(_dist), mod(_mod), type(_type) {};
};
int n;
int dist[N], cnt[N];
vector<event> events[N];
int sqrt_n;
mint pref[320][320];
mint dp[N];
void solve() {
cin >> n;
sqrt_n = sqrt(n);
for (int i = 1; i <= n; ++ i) {
cin >> dist[i] >> cnt[i];
if (cnt[i] == 0 || dist[i] == 0) continue;
if (dist[i] <= sqrt_n) {
int first = i + dist[i];
int last = i + min((n - i) / dist[i], cnt[i]) * dist[i];
if (first <= n) {
events[first].push_back(event(i, dist[i], i % dist[i], 1));
}
if (last + dist[i] <= n) {
events[last + dist[i]].push_back(event(i, dist[i], i % dist[i], -1));
}
}
}
dp[1] = 1;
for (int i = 1; i <= n; ++ i) {
for (const auto& [idx, d, mod, sign] : events[i]) {
// cout << idx << ' ' << d << ' ' << mod << ' ' << sign << '\n';
pref[d][mod] += mint(sign) * dp[idx];
}
for (int dist = 1; dist <= sqrt_n; ++ dist) {
dp[i] += pref[dist][i % dist];
}
if (dist[i] > sqrt_n) {
for (int j = 1; j <= cnt[i]; ++ j) {
int nxt = i + j * dist[i];
if (nxt > n) break;
dp[nxt] += dp[i];
}
}
}
mint res = 0;
for (int i = 1; i <= n; ++ i) {
// cout << dp[i] << " \n"[i == n];
res += dp[i];
}
cout << res;
}
int32_t main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(nullptr); std::cout.tie(nullptr);
// int t; cin >> t;
int t = 1;
while (t-- > 0) {
solve();
cout << '\n';
}
return (0 ^ 0);
}
/// Code by vuavisao
