#include<bits/stdc++.h>
using namespace std;
const int MAXN=1e5+5;
const int sqr=320;
const long long mod=1e9+7;
long long dp[MAXN],pref[MAXN][sqr+5],A[MAXN],B[MAXN];
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n;
cin>>n;
dp[1]=1;
long long ans=0;
for(int i=1;i<=n;i++)
{
cin>>A[i]>>B[i];
for(int j=1;j<=sqr;j++)
{
if(i>=j) pref[i][j]=(pref[i][j]+pref[i-j][j])%mod;
dp[i]=(dp[i]+pref[i][j])%mod;
}
ans=(ans+dp[i])%mod;
if(A[i]&&A[i]<=sqr)
{
if(B[i]) pref[i+A[i]][A[i]]=(pref[i+A[i]][A[i]]+dp[i])%mod;
if(i+A[i]*(B[i]+1)<=n) pref[i+A[i]*(B[i]+1)][A[i]]=(pref[i+A[i]*(B[i]+1)][A[i]]-dp[i]+mod)%mod;
}
else if(A[i]) for(int j=i+A[i],cnt=1;j<=n&&cnt<=B[i];j+=A[i],cnt++) dp[j]=(dp[j]+dp[i])%mod;
}
cout<<ans;
}
