#include <bits/stdc++.h>
using namespace std;
const long long buc=316,mod=1000000007;
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
pair<long long,long long> arr[n+1];
for(int i=1; i<=n; i++) cin >> arr[i].first >> arr[i].second;
long long dp[n+1];
memset(dp,0,sizeof(dp));
dp[1]=1;
long long smol[buc+5][buc+5]; //div, rem
memset(smol,0,sizeof(smol));
vector<pair<int,long long> > stop[n+1];
long long ans=0;
for(int i=1; i<=n; i++){
for(int j=1; j<buc; j++){
dp[i]+=smol[j][i%j];
dp[i]%=mod;
}
ans+=dp[i];
ans%=mod;
for(auto j:stop[i]){
smol[j.first][i%j.first]-=j.second;
smol[j.first][i%j.first]%=mod;
if(smol[j.first][i%j.first]<0) smol[j.first][i%j.first]+=mod;
}
if(arr[i].first==0) continue;
else if(arr[i].first<buc){
smol[arr[i].first][i%arr[i].first]+=dp[i];
smol[arr[i].first][i%arr[i].first]%=mod;
if(i+arr[i].first*arr[i].second<=n){
stop[i+arr[i].first*arr[i].second].push_back({arr[i].first,dp[i]});
}
}
else{
for(int j=1; j<=arr[i].second; j++){
if(i+j*arr[i].first>n) break;
dp[i+j*arr[i].first]+=dp[i];
dp[i+j*arr[i].first]%=mod;
}
}
}
cout << ans;
}
