#include <bits/stdc++.h>
using namespace std;
#define int long long
#define f first
#define s second
#define pll pair<int,int>
#define g0(x) get<0>(x)
#define g1(x) get<1>(x)
#define g2(x) get<2>(x)
const int bk=350;
const int lm=1000000007;
int way[100005];
vector<vector<int>> mod(bk+10);
vector<vector<tuple<int,int,int>>> rm(100005);
vector<pll> v(100005);
signed main(){
int n;cin>>n;
for(int i=1;i<=bk;i++){
mod[i].resize(i);
}
for(int i=0;i<n;i++){
cin>>v[i].f>>v[i].s;
}
way[0]=1;
for(int i=0;i<n;i++){
int s=v[i].f, t=v[i].s;
//~ cout<<i<<endl;
for(int m=1;m<bk;m++){
//~ printf("m %lld, i mod m %lld, contrib %lld\n", m,i%m, mod[m][i%m]);
way[i]+=mod[m][i%m];
way[i]%=lm;
}
if(s != 0){
if(n > bk * s){
mod[s][i%s]=(mod[s][i%s]+way[i])%lm;
if(i + t*s < n) rm[i+t*s].push_back({s,i%s,way[i]});
}
else{
for(int j=1;j<=t and i+j*s < n;j++){
way[i+j*s]=(way[i+j*s]+way[i])%lm;
}
}
}
for(auto [m, r, rmv]:rm[i]){
mod[m][r]-=rmv;
while(mod[m][r]<0)mod[m][r]+=lm;
}
//~ for(int j=0;j<n;j++){
//~ cout<<way[j]<<' ';
//~ }
//~ cout<<endl<<endl;
}
int ans=0;
for(int i=0;i<n;i++){
//~ cout<<way[i]<<" ";
ans+=way[i];
ans%=lm;
}
//~ cout<<endl;
cout<<ans;
}
