#include<bits/stdc++.h>
using namespace std;
constexpr long long MOD=1e9+7;
vector<long long>rs;
//vector<vector<int>>ad;
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N;
cin>>N;
rs.resize(N);
//ad.resize(N);
long long d,x;
rs[0]=1;
long long ris=0;
for(int i=0;i<N;i++){
cin>>d>>x;
//cout<<"i: "<<i<<" - "<<rs[i]<<endl;
ris=(ris+rs[i])%MOD;
if(d==0 or rs[i]==0)continue;
long long mx=min(d*x+i,(long long)N-1);
for(int ns=i+d;ns<=mx;ns+=d){
// int ns=i+t*d;
// if(ns>=N)break;
//ad[i].push_back(i+t*d);
rs[ns]=(rs[ns]+rs[i])%MOD;
}
//cout<<"!"<<endl;
}
cout<<ris<<endl;
}
