//#pragma GCC optimize("Ofast,unroll-loops")
//#pragma GCC target("avx,avx2,fma,lzcnt,popcnt")
#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define pb push_back
#define pf push_front
#define ii pair<int,int>
#define ill pair<ll,ll>
#define el cout<<'\n'
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define int long long
const ll mod=1e9+7;
const int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
const int nmax=1e5;
void add ( int&a , int b ) { if ((a+=b) > mod ) a -= mod ; }
void sub ( int&a , int b ) { if ((a-=b) < 0 ) a += mod ; }
template<typename T> void chkmin(T& x, T y) {if(x > y) x = y;}
template<typename T> void chkmax(T& x, T y) {if(x < y) x = y;}
using namespace std;
int d[nmax+5];
int x[nmax+5];
int dp[nmax+5];
signed main()
{
ios::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
int n;
cin>>n;
for(int i=1;i<=n;i++)
cin>>d[i]>>x[i];
if(n<=10000)
{
int ans=0;
dp[1]=1;
for(int i=1;i<=n;i++)
{
if(d[i]>=1)
for(int j=i+1*d[i];j<=min(n,i+d[i]*x[i]);j+=d[i])
dp[j]=(dp[j]+dp[i])%mod;
// cout<<"Wtf"<<i;el;
}
for(int i=1;i<=n;i++)
ans=(ans+dp[i])%mod;
cout<<ans;el;
}
}
