#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], pfs[N][501];
void sol()
{
cin >> n;
for(int i=1; i<=n; i++) cin >> d[i] >> x[i];
for(int i=n; i>=1; i--)
{
dp[i]=1;
if(d[i]>=500) for(int j=1; j<=x[i] && i+j*d[i]<=n; j++) dp[i]=(dp[i]+dp[i+j*d[i]])%mod;
else if(d[i])
{
if(i+d[i]<=n) dp[i]=(dp[i]+pfs[i+d[i]][d[i]])%mod;
if(i+d[i]*(x[i]+1ll)<=n) dp[i]=(dp[i]-pfs[i+d[i]*(x[i]+1ll)][d[i]])%mod;
}
for(int j=1;j<500;j++)
{
pfs[i][j]=dp[i];
pfs[i][j]=(pfs[i][j]+pfs[i+j][j])%mod;
}
}
cout << (dp[1]+mod)%mod;
}
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();
}
}
