#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 rem[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++) {
ll d, x;
cin >> d >> x;
if (d >= B && d <= n) {
l[i].push_back(d);
for (int c = 1; c < x && i + c * d <= n; c++) {
l[i + c * d].push_back(d);
}
} else if (d > 0 && d < B) {
rem[i][d] = max(rem[i][d], (int) x);
}
for (int j = 1; j < B; j++) {
if (rem[i][j] > 0 && i + j <= n) {
(dp[i + j] += dp[i]) %= mod;
rem[i + j][j] = rem[i][j] - 1;
}
}
for (int j : l[i]) {
if (i + j <= n && !used[j]) {
used[j] = 1;
(dp[i + j] += dp[i]) %= mod;
}
}
for (int j : l[i]) {
used[j] = 0;
}
(ans += dp[i]) %= mod;
}
cout << ans << '\n';
return 0;
}
