#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
const int maxn = 1e5 + 10;
int x[maxn];
int d[maxn];
int dp[maxn];
map<int, int> resp[maxn];
int n;
int sum (int a, int b) {
return (((a + b) % mod) + mod) % mod;
}
int aux(int i, int d) {
if (d == 0) return 0;
if (i >= n) return 0;
if (i == n - 1) return 1;
if (resp[i].count(d)) return resp[i][d];
int ans = sum(dp[i], aux(i + d, d));
//cerr << i << ' ' << d << ' ' << " = " << ans << '\n';
return resp[i][d] = ans;
}
int main () {
cin >> n;
for (int i = 0; i < n; i++) {
cin >> d[i] >> x[i];
}
dp[n - 1] = 1;
for (int i = n - 2; i >= 0; i--) {
//cerr << i + d[i] << ' ' << d[i] << '\n';
int t1 = aux(i + d[i], d[i]);
int t2 = aux(i + (x[i] + 1) * d[i], d[i]);
//cerr << "for " << i << " = 1 + " << t1 << " - " << t2 << '\n';
dp[i] = sum(
sum(1, t1),
-t2
);
}
for (int i = 0; i < 1; i++) {
cout << dp[i] << ' ';
}
}
