#include <bits/stdc++.h>
#define el '\n'
#define FNAME "trains"
#define allof(x) x.begin(),x.end()
#define allof1(x) x.begin()+1,x.end()
#define mset(x,n) memset(x,(n),sizeof(x))
using namespace std;
const long long MOD = (long long) 1e9+7;
template<class X,class Y> bool minimize(X &a,Y b){ if (a>b) {a=b; return true;} return false;}
template<class X,class Y> bool maximize(X &a,Y b){ if (a<b) {a=b; return true;} return false;}
void setup(){
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
if (fopen(FNAME".inp","r")){
freopen(FNAME".inp","r",stdin);
freopen(FNAME".out","w",stdout);
}
}
struct Train{
long long d,x;
int ID;
Train(): d(0),x(0),ID(-1){}
Train(long long D,long long X,int _ID): d(D), x(X),ID(_ID){}
bool canTravel(int cID){
if (!d) return false;
if (cID<=ID or ID==-1) return false;
cID -= ID;
if (cID % d) return false;
return (cID/d <= x);
}
};
int n;
vector<Train> a;
void init(){
cin>>n;
a.assign(n+1,Train());
for (int i=1;i<=n;i++){
cin>>a[i].d>>a[i].x;
a[i].ID=i;
}
}
inline void add(long long &x,long long y){
x+=y;
if (x>=MOD) x-=MOD;
}
namespace BruteDP{
void solve(){
// ! dp[i]: # of ways to get to city i and ending at city i from city 1
vector<long long> dp(n+1,0);
dp[1] = 1;
for (int i=2;i<=n;i++){
for (int j=i-1;j>=1;j--){
if (a[j].canTravel(i)) add(dp[i],dp[j]);
}
}
long long res = 0;
for (int i=1;i<=n;i++) add(res,dp[i]);
cout<<res;
exit(0);
}
};
namespace FinalDP{
/*
! jumpSum[jump][r]: sum accumulated with Jump jump, remainder r
* jump update is written in form i + t * x
? i.e, destination of 2 (d=3) 2 + 1 * 3 = 5, 2 + 2*3= 8, 14, 17
? Notice how all destination of 2 all have remainder 2 under modulo 3
? also more 3,4...
* => i % jump = r returns correctly to its starting place
*/
vector<vector<long long>> jumpSum;
// ! lazy[i][jump]
// ? difference array to lazily update jumpSum
vector<vector<long long>> lazy;
int S;
void range(int ID,int jump,long long delta){
if (ID>n) return;
if (delta < 0) delta+=MOD;
add(lazy[ID][jump],delta);
}
void solve(){
S = static_cast<int>(sqrt(n)) + 1;
jumpSum.assign(S+1,vector<long long>(S+1,0));
lazy.assign(n+1,vector<long long>(S+1,0));
vector<long long> dp(n+1,0);
dp[1] = 1;
for (int i=1;i<=n;i++){
for (int jump=1;jump<S;jump++){
int r = i%jump;
add(jumpSum[jump][r],lazy[i][jump]);
add(dp[i],jumpSum[jump][r]);
}
if (!a[i].d) continue;
if (a[i].d < S){
long long jump = a[i].d;
range(i + jump,jump,+dp[i]);
if (jump * (a[i].x+1) + i <=n)
range(i + jump * (a[i].x+1),jump,-dp[i]);
} else{
long long x = a[i].x;
long long jump = a[i].d;
for (long long j=i + jump,t=1; t<=x and j<=n; j+=jump, t++)
add(dp[j],dp[i]);
}
}
long long res=0;
for (int i=1;i<=n;i++) add(res,dp[i]);
cout<<res;
exit(0);
}
};
void sol(){
if (n<=1e4) BruteDP::solve();
FinalDP::solve();
}
int main(){
setup();
init();
sol();
}
