#include<bits/stdc++.h>
using namespace std;
#ifdef DEBUG
auto& operator <<(auto& o, pair<auto, auto> p) {return o<<"{"<<p.first<<", "<<p.second<<"}";}
auto& operator <<(auto& o, auto x) {o<<"{"; for(auto v : x) o<<v<<", "; return o<<"}";}
#define debug(X) cerr<<"["#X"]: "<<X<<endl;
#else
#define debug(X) {}
#endif
#define int long long
const int MOD = 1e9+7;
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n;
cin>>n;
vector<int> dp(n);
vector<pair<int, int> > trains(n);
for(auto& v : trains) cin>>v.first>>v.second;
for(int i=n-1;i>=0;i--)
{
int d = trains[i].first, x = trains[i].second;
if(d == 0) continue;
for(int k = i+d;k<=i+d*x && k < n;k+=d)
{
dp[i] += dp[k] + 1;
dp[i] %= MOD;
}
}
cout<<(dp[0]+1)%MOD;
}
