#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll mod = 1e9 + 7;
ll f(ll cr,ll n,map<ll,ll> &x,map<ll,ll> &d,vector<ll>&dp){
if(cr>n) return 0;
ll am = 1;
if(d[cr]==0) return am;
if(dp[cr]!=-1) return dp[cr];
for(ll i=1;i<=x[cr];i++){
ll newDes = cr + i*d[cr];
if(newDes>n) break;
am = (am + f(newDes,n,x,d,dp))%mod;
}
return dp[cr] = (am)%mod;
}
void solve(){
ll n;
cin>>n;
map<ll,ll> d,x;
vector<ll> dp(1e5 + 10,-1);
for(ll i=1;i<=n;i++){
ll a,b;
cin>>a>>b;
d[i]=a;
x[i]=b;
}
ll ans = f(1,n,x,d,dp);
cout<<ans<<endl;
}
int main()
{
// freopen("input.txt","r",stdin);
// freopen("output.txt","w",stdout);
ios::sync_with_stdio(false);
cin.tie(NULL);
solve();
return 0;
}
