#include<bits/stdc++.h>
using namespace std;
#define FOR(i ,a ,b) for(int i = a; i <= b; i++)
const int maxN = 1e5 + 999;
const int mod = 1e9 + 7;
int n , d[maxN] , x[maxN];
namespace sub1{
long long dp[maxN];
bool check(){
return (n <= 5000);
}
void solve(){
dp[1] = 1;
FOR(i, 1, n){
if(d[i] == 0)continue;
FOR(j ,1 , x[i]){
long long nxt = i + 1LL * j * d[i];
if(nxt > n)break;
dp[nxt] = (dp[nxt] + dp[i])%mod;
}
}
long long ans = 0;
FOR(i, 1, n){
ans = (ans + dp[i])%mod;
}
cout << ans;
}
}
namespace ac{
int B;
void Fixmod(int & x){
if(x >= mod) x-=mod;
if(x < 0)x += mod;
}
int dp[maxN];
int cnt[320][maxN];
void solve(){
B = sqrt(n);
dp[1] = 1;
FOR(i, 1, n){
FOR(j, 1 , B){
if(i - j < 1)break;
cnt[j][i] = (cnt[j][i] + cnt[j][i - j])%mod;
Fixmod(cnt[j][i]);
dp[i] = (dp[i] + cnt[j][i])%mod;
Fixmod(dp[i]);
}
///update
if(d[i] > B){
FOR(j ,1 , x[i]){
long long nxt = i + 1LL * j * d[i];
if(nxt > n)break;
dp[nxt] = (dp[nxt] + dp[i])%mod;
}
}else{
if(d[i] == 0)continue;
cnt[d[i]][i] = (cnt[d[i]][i] + dp[i])%mod;
Fixmod(cnt[d[i]][i]);
long long kk = (i + 1LL* (x[i] + 1)* d[i]);
if(kk <= n){
cnt[d[i]][kk] = (cnt[d[i]][kk] - dp[i]);
Fixmod(cnt[d[i]][kk]);
}
}
}
int ans =0 ;
FOR(i, 1, n){
ans = (ans + dp[i])%mod;
Fixmod(ans);
}
cout << ans;
// cerr << ans << '\n';
}
}
void solve(){
cin >> n ;
FOR(i, 1 , n){
cin >> d[i] >> x[i];
}
// cout << sqrt(1e5);
if(sub1::check())return sub1::solve();
return ac::solve();
}
const string NAME = "task";
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
// freopen("train.inp", "r" ,stdin);
// freopen("train.out", "w" ,stdout);
// freopen(NAME +"out", "w" , stdout);
solve();
}
