// Author: Ivan Teo
// Created: Wed Jul 31 18:10:56 2024
#define TASKNAME "BOITRAINS"
#include <bits/stdc++.h>
using namespace std;
#define fore(i, a, b) for (int i = (a); i <= (b); i++)
#define ford(i, a, b) for (int i = (a); i >= (b); i--)
#define int long long
using vi = vector<int>;
using ii = pair<int, int>;
#define pb emplace_back
#define fi first
#define se second
#define sz(v) ((int)v.size())
#define all(v) v.begin() + 1, v.end()
#define alll(v) v.begin(), v.end()
#define db(x) cerr << "[" << #x << " = " << x << "]"
#define ell cerr << "\n=========================================\n"
#define el cerr << '\n'
#define Unique(v) v.erase(unique(alll(v)), v.end())
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
int Rand(int l, int r)
{
assert(l <= r);
return uniform_int_distribution<int> (l, r)(rng);
}
template<int D, typename T> struct Vec : public vector < Vec < D - 1, T >>
{
template<typename... Args> Vec(int n = 0, Args... args) : vector < Vec < D - 1, T >> (n, Vec < D - 1, T > (args...)) {}
};
template<typename T> struct Vec<1, T> : public vector<T>
{
Vec(int n = 0, const T &val = T()) : vector<T>(n, val) {}
};
const int N = 1e5 + 5;
const int BLOCK = sqrt(N);
const int MOD = 1e9 + 7;
int add(int a, int b)
{
a += b;
if (a < 0) a += MOD;
if (a >= MOD) a -= MOD;
return a;
}
int f[N], rem[N][BLOCK], n, d[N], x[N];
vector<ii> ev[N];
void ivan()
{
cin >> n;
fore(i, 1, n) cin >> d[i] >> x[i];
f[1] = 1;
fore(i, 1, n)
{
if (d[i] < BLOCK)
rem[i][d[i]] = add(rem[i][d[i]], f[i]),
ev[min(N - 1, i + d[i] * x[i])].pb(d[i], f[i]);
for (auto [d, x] : ev[i]) rem[i][d] = add(rem[i][d], -x);
fore(j, 1, BLOCK)
if (i + j <= n)
rem[i + j][j] = add(rem[i][j], rem[i + j][j]),
f[i + j] = add(f[i + j], rem[i][j]);
if (d[i] >= BLOCK)
{
fore(cnt, 1, x[i])
{
if (i + cnt * d[i] <= n)
{
int j = i + cnt * d[i];
f[j] = add(f[j], f[i]);
}
else break;
}
}
}
int ans = 0;
fore(i, 1, n) ans = add(ans, f[i]);
cout << ans;
}
signed main()
{
cin.tie(0)->sync_with_stdio(0);
if (fopen(TASKNAME".inp", "r"))
{
freopen(TASKNAME".inp", "r", stdin);
freopen(TASKNAME".out", "w", stdout);
}
int tc = 1;
// cin >> tc;
while (tc--) ivan();
el, cerr << "Execution Time: " << 1.0 * clock() / CLOCKS_PER_SEC << "s", el;
return 0;
}
