#include <bits/stdc++.h>
#define f first
#define s second
#define int long long
using namespace std;
const int N = 2e5 + 69;
const int mod = 1e9 + 7;
int n, d[N], x[N], dp[N];
int add(int x, int y) {
x += y;
if (x >= mod)
x -= mod;
return x;
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int tt = 1;
//cin >> tt;
while (tt--) {
cin >> n;
for (int i = 1;i <= n;i++)
cin >> d[i] >> x[i];
dp[1] = 1;
for (int i = 1;i <= n;i++) {
if (d[i] == 0)
continue;
for (int j = i + d[i], j1 = 1;j <= n && j1 <= x[i];j += d[i], j1++)
dp[j] = add(dp[j], dp[i]);
}
int ans = 0;
for (int i = 1;i <= n;i++)
ans = add(ans, dp[i]);
cout << ans;
}
return 0;
}
