/* 29 . 03 . 2008 */
#include <bits/stdc++.h>
using namespace std ;
bool watbor = 0 ;
#define int long long
typedef long long ll ;
typedef vector<int> vi ;
typedef vector<pair<int,int>> vii ;
typedef pair<int,int> pii ;
typedef pair<ll,int> pli ;
typedef pair<int,ll> pil ;
typedef pair<ll,ll> pll ;
#define FOR(i,a,b) for(int i(a) ; i <= (int)b ; i++)
#define FORD(i,a,b) for(int i(a) ; i >= (int)b ; i--)
#define FORN(i,a,b) for(int i(a) ; i < (int)b ; i++)
#define all(a) a.begin() , a.end()
#define pb push_back
#define fi first
#define se second
#define endl '\n'
#define BIT(mask,i) ((mask>>i)&1)
#define builtin_popcount builtin_popcountll
#define uni(a) sort(all(a)), a.resize(unique(all(a))-a.begin())
#define MASK(a) (1ll << a)
int gcd(int x, int y) {return __gcd(x, y) ;}
int lg(int x) {return __lg(x) ;}
int lcm(int x, int y) {return x / __gcd(x, y) * y ;}
template <class T> bool maxi(T &x,T y) { if (x < y) { x = y ; return true ;} return false ;}
template <class T> bool mini(T &x,T y) { if (x > y) { x = y ; return true ;} return false ;}
const int N = 2e5 + 5, M = 5e3 + 5, LG = __lg(N) + 1, base = 311 ;
const int oo = 2e9, sm = 1e9 + 7, mod1 = 1e9 + 7, mod2 = 998244353 ;
const long long inf = 1e18 ;
void add(int &x, const int y) {
x+= y ;
if(x >= sm) x-= sm ;
}
int n ;
pair <int, int> a[N] ;
void init() {
cin >> n ;
FOR(i, 1, n)
cin >> a[i].fi >> a[i].se ;
}
namespace subtask_1 {
bool check() {return n <= 5e3 ;}
int dp[N] ;
void solve() {
dp[1] = 1 ;
FOR(i, 1, n) FOR(t, i + 1, n) {
int so = (t - i) ;
if(a[i].fi == 0) continue ;
if(so % a[i].fi == 0 && so / a[i].fi <= a[i].se)
add(dp[t], dp[i]) ;
}
int ans = 0 ;
FOR(i, 1, n) add(ans, dp[i]) ;
cout << ans ;
}
}
namespace subtask_2 {
bool check() {FOR(i, 1, n) if(a[i].fi != 1) return 0; return 1;}
int dp[N] ;
int st[4 * N], lazy[4 * N] ;
void down(int id, int l, int r) {
if(lazy[id] == 0) return ;
int mid = (l + r) >> 1 ;
st[id << 1]+= 1ll * (mid - l + 1) * lazy[id] ;
st[id << 1 | 1]+= 1ll * (r - mid) * lazy[id] ;
if(st[id << 1] >= sm) st[id << 1] -= sm ;
if(st[id << 1 | 1] >= sm) st[id << 1 | 1] -= sm ;
lazy[id << 1]+= lazy[id] ;
lazy[id << 1 | 1]+= lazy[id] ;
if(lazy[id << 1] >= sm) lazy[id << 1]-= sm ;
if(lazy[id << 1 | 1] >= sm) lazy[id << 1 | 1]-= sm ;
lazy[id] = 0 ;
}
void up(int id, int l, int r, int u, int v, int val) {
if(l > v || r < u) return ;
if(l >= u && r <= v) {
st[id]+= 1ll * (r - l + 1) * val ;
lazy[id]+= val ;
if(st[id] >= sm) st[id]-= sm ;
if(lazy[id] >= sm) lazy[id]-= sm ;
return ;
}
down(id, l, r) ;
int mid = (l + r) >> 1 ;
up(id << 1, l, mid, u, v, val) ;
up(id << 1 | 1, mid + 1, r, u, v, val) ;
st[id] = (st[id << 1] + st[id << 1 | 1]) % sm ;
}
int get(int id, int l, int r, int u, int v) {
if(l > v || r < u) return 0 ;
if(l >= u && r <= v) return st[id] ;
int mid = (l + r) >> 1 ;
down(id, l, r) ;
return (get(id << 1, l, mid, u, v) + get(id << 1 | 1, mid + 1, r, u, v) ) % sm ;
}
void solve() {
dp[1] = 1 ;
up(1, 1, n, 1, min(n, 1 + a[1].se), 1) ;
FOR(i, 2, n) {
dp[i] = get(1, 1, n, i, i) ;
up(1, 1, n, i + 1, min(n, i + a[i].se), dp[i]) ;
}
int ans = 0 ;
FOR(i, 1, n) add(ans, dp[i]) ;
cout << ans ;
}
}
namespace subtask_3 {
bool check() {
FOR(i, 1, n) if(a[i].se != n) return 0 ;
return 1 ;
}
int dp[N] ;
void solve() {
FOR(i, 1, n) {
if(i == 1) dp[i] = 1 ;
for(int j = 0; j <= a[i].se; j++) {
if(i + 1ll * j * a[i].fi > n) break ;
if(i + 1ll * j * a[i].fi <= i) continue ;
add(dp[i + 1ll * j * a[i].fi], dp[i]) ;
}
}
int ans = 0 ;
FOR(i, 1, n) add(ans, dp[i]) ;
cout << ans ;
}
}
int32_t main() {
ios_base::sync_with_stdio(0) ; cin.tie(0) ; cout.tie(0) ;
#define task ""
if(fopen(task".inp","r")) {
freopen(task".inp","r",stdin) ;
freopen(task".out","w",stdout) ;
}
int tc ; tc = 1 ;
if(watbor) cin >> tc ;
FOR(bqc, 1, tc) {
init() ;
if(subtask_1::check()) return subtask_1::solve(), 0 ;
if(subtask_2::check()) return subtask_2::solve(), 0 ;
return subtask_3::solve(), 0 ;
}
cerr << "\nTime : " << clock() * 0.001 << "s" << endl ;
return 0 ;
}
/* Watbor */
