#include "bits/stdc++.h"
using namespace std;
const int maxn = 1e5 + 5;
const int B = 350;
const int mod = 1e9 + 7;
int n, d[maxn], x[maxn];
int f[maxn], g[maxn][B];
int add(int x, int y) {
if(y < 0) y += mod;
x = x + y;
if(x >= mod) x -= mod;
return x;
}
void solve() {
cin >> n;
for(int i = 1; i <= n; ++i) {
cin >> d[i] >> x[i];
}
f[1] = 1;
for(int i = 1; i <= n; ++i) {
for(int j = 1; j < B; ++j) {
if(j < i) g[i][j] = add(g[i][j], g[i - j][j]);
f[i] = add(f[i], g[i][j]);
}
if(d[i] < B) {
g[i][d[i]] = add(g[i][d[i]], f[i]);
long long en = 1ll * d[i] * (x[i] + 1) + i;
if(en <= n) g[en][d[i]] = add(g[en][d[i]], -f[i]);
}
else {
for(int cnt = 1, j = i + d[i]; cnt <= x[i] and j <= n; j += d[i], ++cnt) {
f[j] = add(f[j], f[i]);
}
}
}
int ans = 0;
for(int i = 1; i <= n; ++i) {
ans = add(ans, f[i]);
}
cout << ans;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
