#include<bits/stdc++.h>
#define el '\n'
#define fi first
#define sc second
#define int ll
#define pii pair<int, int>
#define all(v) v.begin(), v.end()
using namespace std;
using ll=long long;
using ull=unsigned long long;
using ld=long double;
const int mod=1e9+7;
const int N=1e5+11;
int n, d[N], x[N], dp[N];
void sol()
{
cin >> n;
for(int i=1;i<=n;i++) cin >> d[i] >> x[i];
dp[1]=1;
for(int i=2;i<=n;i++)
{
for(int j=1;j<i;j++)
{
if(d[j]==0) continue;
if((i-j)%d[j]!=0) continue;
if((i-j)/d[j]>x[j]) continue;
dp[i]=(dp[i]+dp[j])%mod;
}
}
int ans=0;
for(int i=1;i<=n;i++) ans=(ans+dp[i])%mod;
cout << ans;
}
signed main()
{
// freopen("divisor.INP", "r", stdin);
// freopen("divisor.OUT", "w", stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
int t=1;
//cin >> t;
while(t--)
{
sol();
}
}
