#include <bits/stdc++.h>
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")
#define fio ios_base::sync_with_stdio(0);cin.tie(0);
#define en cin.close();return 0;
#define ll long long
#define fi first
#define se second
using namespace std;
const int N = 1e5+5;
const int SQ = sqrt(N)+2;
const int mod = 1e9+7;
int pf[N][SQ], dp[N];
int sum(int a, int b)
{
a+=b;
if(a>=mod)
a-=mod;
if(a<0)
a+=mod;
return a;
}
int mul(int a, int b)
{
return 1ll*a*b%mod;
}
int main()
{
fio
// ifstream cin("in.in");
int n;
cin >> n;
int sq = sqrt(n), res = 0;
dp[1]=1;
for(int i = 1;i<=n;i++)
{
for(int j = 1;j<=sq;j++)
{
if(i-j>=0)
pf[i][j]=sum(pf[i][j],pf[i-j][j]);
dp[i]=sum(dp[i],pf[i][j]);
}
res=sum(res,dp[i]);
int d, x;
cin >> d >> x;
if(!d)
continue;
if(d>sq)
{
for(int j = 1;j<=x&&i+j*d<=n;j++)
dp[i+j*d]=sum(dp[i+j*d],dp[i]);
}
else
{
if(i+d<=n)
pf[i+d][d]=sum(pf[i+d][d],dp[i]);
if(i+1ll*(x+1)*d<=n)
pf[i+(x+1)*d][d]=sum(pf[i+(x+1)*d][d],-dp[i]);
}
}
cout << res;
return 0;
}
