#include <bits/stdc++.h>
using namespace std;
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii ;
typedef pair<ll, ll> pll ;
typedef vector<pii> vii ;
typedef vector<int> veci ;
typedef vector<pll> vll ;
typedef vector<ll> vecll;
// find_by_order order_of_key
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define F first
#define S second
#define pb push_back
#define endl '\n'
#define Mp make_pair
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " = " << x << endl
#define set_dec(x) cout << fixed << setprecision(x);
#define fast_io ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io freopen("in.txt" , "r" , stdin) ; freopen("out.txt" , "w" , stdout);
#define lb lower_bound
#define ub upper_bound
#define for1(n) for(int i=1;i<=n;i++)
#define for0(n) for(int i=0;i<n;i++)
#define forn(n) for(int i=n;i>0;i--)
#define pq priority_queue <pii, vector<pii>, greater<pii>>
const int mod=1e9+7;
const int N=1e5+3;
int n,m,k,q;
ll dp[N];
unordered_map<int,ll>C[N];
int main(){
fast_io
cin>>n;
dp[1]=1;
ll ans=0;
for1(n){
dp[i]%=mod;
ans+=dp[i];
int x,y;cin>>x>>y;
if(x!=0){
C[i][x]+=dp[i];
if(ll(i)+1ll*x*y<=n)
C[i+x*y][x]+=+mod-dp[i];
}
for(pii p:C[i]){
p.S%=mod;
if(p.S!=0){
if(i+p.F<=n){
C[i+p.F][p.F]+=p.S;
dp[i+p.F]+=p.S;
}
}
}
}
cout<<ans%mod<<endl;
}
