#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(x) (x).begin(), (x).end()
const int mod = 1e9 + 7;
const int N = 1e5 + 7, B = 320;
int n;
int p[N][B];
ll dp[N];
vector<int> l[N];
bool used[N];
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
dp[1] = 1;
ll ans = 0;
for (int i = 1; i <= n; i++) {
int d, x;
cin >> d >> x;
for (int j = 1; j < B; j++) {
if (i - j >= 0) {
(p[i][j] += p[i - j][j]) %= mod;
}
(dp[i] += p[i][j]) %= mod;
}
if (d >= B && d <= n) {
for (int c = 1; c <= x && i + c * d <= n; c++) {
(dp[i + c * d] += dp[i]) %= mod;
}
} else if (d > 0 && d < B) {
int stops = min(x, (n - i) / d);
if (stops >= 1) {
(p[i + d][d] += dp[i]) %= mod;
if (i + d * (stops + 1) <= n) {
(p[i + d * (stops + 1)][d] += mod - dp[i]) %= mod;
}
}
}
(ans += dp[i]) %= mod;
}
cout << ans << '\n';
return 0;
}
