/*
بسم الله الرحمن الرحيم
Author:
(:Muhammad Aneeq:)
*/
#include <iostream>
#include <map>
using namespace std;
int const mod=1e9+7;
inline void solve()
{
int n;
cin>>n;
int d[n],x[n];
for (int i=0;i<n;i++)
cin>>d[i]>>x[i];
int ans[n]={};
map<int,int>val[n]={};
ans[0]=1;
for (int i=0;i<n;i++)
{
for (auto& j:val[i])
{
ans[i]+=j.second;
ans[i]%=mod;
}
if (d[i]&&x[i]&&i+d[i]<n)
{
val[i+d[i]][d[i]]+=ans[i];
if (i+d[i]*x[i]+d[i]<n)
{
val[i+d[i]*x[i]+d[i]][d[i]]+=(mod-ans[i]);
val[i+d[i]*x[i]+d[i]][d[i]]%=mod;
}
}
for (auto& j:val[i])
{
if (i+j.first<n&&j.second!=0)
{
val[i+j.first][j.first]+=j.second;
val[i+j.first][j.first]%=mod;
}
}
val[i]={};
}
int z=0;
for (auto i:ans)
z=(z+i)%mod;
cout<<z<<endl;
}
signed main()
{
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
solve();
}
