#include <bits/stdc++.h>
using namespace std;
#define ff endl
#define lf "\n"
#define fi first
#define se second
#define _ << ' ' <<
#define all(x) begin(x),end(x)
#define rall(x) rbegin(x),rend(x)
#ifdef DEBUG
constexpr bool IS_DEBUG = 1;
#define infor(fmt, ...) do { print(stderr, fmt, ##__VA_ARGS__); } while(0)
#define infof(fmt, ...) do { println(stderr, fmt, ##__VA_ARGS__); } while(0)
#else
constexpr bool IS_DEBUG = 0;
#define infor(fmt, ...)
#define infof(fmt, ...)
#endif
using ll = long long;
using pll = pair<ll, ll>;
using pii = pair<int, int>;
template<typename... Args>
using vec = vector<Args...>;
constexpr int LOG = 20;
constexpr int MOD = 1e9+7;
constexpr int MAXN = 1e5+7;
mt19937 timmy_loves_gambling(73);
int add(int a, int b) {
int x = a + b;
return x < MOD ? x : x - MOD;
}
void chadd(int &a, int b) {
a = add(a, b);
}
int mul(int a, int b) {
return (ll)a * b % MOD;
}
void chmul(int &a, int b) {
a = mul(a, b);
}
int main(void) {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int N; cin >> N;
vec<int> K(N), R(N);
for(int i = 0; i < N; ++i) {
cin >> K[i] >> R[i];
if(K[i] >= N - i) K[i] = 0;
if(K[i] == 0) continue;
R[i] = min(R[i], (N - i - 1) / K[i]);
}
vec<int> dp(N, 1);
vec<map<int, int>> sfx(2 * N);
auto calc = [&](int i, int k, int r, auto &&calc) -> int {
if(i >= r) return 0;
auto it = sfx[i].find(k);
if(it != sfx[i].end()) return it->se;
return sfx[i][k] = add(dp[i], calc(i + k, k, r, calc));
};
for(int i = N - 1; i >= 0; i--) {
if(K[i] == 0) continue;
int l = i + K[i];
int r = i + K[i] * (R[i] + 1);
calc(i + K[i], K[i], r, calc);
chadd(dp[i], add(sfx[l][K[i]], MOD - sfx[r][K[i]]));
}
cout << dp[0] << lf;
}
