#include <bits/stdc++.h>
#define int long long
using namespace std;
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n; cin >> n;
vector<pair<int, int>> a(n + 1);
for (int i = 1; i <= n; i++) {
cin >> a[i].first >> a[i].second;
}
int block_size = 200;
const int mod = (int) 1e9 + 7;
vector<int64_t> dp(n + 1, 0);
vector<vector<int64_t>> diff(block_size + 5, vector<int64_t> (n + 1, 0));
dp[1] = 1;
int64_t ans = 0;
for (int i = 1; i <= n; i++) {
int d = a[i].first, step = a[i].second;
int64_t ways = dp[i];
for (int j = 1; j <= block_size; j++) {
if (i - j >= 0) diff[j][i] += diff[j][i - j];
diff[j][i] %= mod;
ways += diff[j][i];
ways %= mod;
}
ans += ways;
ans %= mod;
if (d == 0 || step == 0) continue;
if (d >= block_size) {
for (int cur = i + d, j = 1; (cur <= n && j <= step); j++, cur += d) {
if (cur <= n) dp[cur] += ways, dp[cur] %= mod;
}
} else {
if (i + d <= n && step > 0) {
diff[d][i + d] += ways;
diff[d][i + d] %= mod;
int last = i + (step + 1) * d;
if (last <= n) {
diff[d][last] -= ways;
diff[d][last] %= mod;
diff[d][last] += mod;
diff[d][last] %= mod;
}
}
}
}
cout << ans << '\n';
return 0;
}
