#include "bits/stdc++.h"
using namespace std;
const int MOD = 1e9 + 7;
const int K = 300;
int main() {
ios::sync_with_stdio(0), cin.tie(0);
int n; cin >> n;
vector<int> d(n), x(n);
for (int i = 0; i < n; i++)
cin >> d[i] >> x[i];
vector sum(n, vector<long long>(K));
vector<long long> dp(n);
for (int i = n - 1; i >= 0; i--) {
dp[i] = 1;
if (d[i] < K) {
if (d[i] && x[i]) {
int lx = i + d[i];
int rx = i + (x[i] + 1) * d[i];
if (lx < n)
dp[i] = (dp[i] + sum[lx][d[i]]) % MOD;
if (rx < n)
dp[i] = (dp[i] - sum[rx][d[i]]) % MOD;
}
} else {
for (int j = i + d[i], k = 0; j < n && k < x[i]; j += d[i], k++)
dp[i] = (dp[i] + dp[j]) % MOD;
}
while (dp[i] < 0) dp[i] += MOD;
for (int j = 1; j < K; j++) {
sum[i][j] = dp[i];
if (i + j < n)
sum[i][j] = (sum[i][j] + sum[i + j][j]) % MOD;
}
}
cout << dp[0] << '\n';
return 0;
}
