#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define len(x) (ll) x.size()
#define all(x) x.begin(), x.end()
using namespace std;
typedef long long ll;
const int N = 1e5 + 11;
const int mod = 1e9 + 7;
const int SQ = 200;
const ll inf = 2e18 + 12;
ll n;
ll x[N], d[N], p[N], dp[N], s[N][SQ];
void add(ll &a, ll b){
a += b, a %= mod, a += mod, a %= mod;
}
signed main(){
cin >> n, dp[1] = 1;
for(ll i = 1; i <= n; i++) cin >> d[i] >> x[i];
for(ll i = 1; i <= n; i++){
for(ll t = 1; t < SQ; t++) add(dp[i], s[i][t]);
if(d[i] >= SQ){
for(ll t = 1; t <= x[i] && i + t * d[i] <= n; t++) add(dp[i + t * d[i]], dp[i]);
}
else{
if(d[i] && x[i]){
add(s[i][d[i]], dp[i]);
if(i + (x[i] + 1) * d[i] <= n)
add(s[i + (x[i] + 1) * d[i]][d[i]], -dp[i]);
}
}
for(ll t = 1; t < SQ && i + t <= n; t++) add(s[i + t][t], s[i][t]);
}
for(ll i = 2; i <= n; i++) add(dp[1], dp[i]);
cout << dp[1];
}
