#include<algorithm>

#include<cstring>

#include<cstdio>

#include<iostream>

using namespace std;

typedef long long ll;

const int N=5e5+;

const ll mo=1e9+;

int n;

struct node

{

    int k,b;

    int id;

}p[N];

bool cmpk(node a,node b) {return a.k==b.k?a.b<b.b:a.k<b.k;}

bool cmpb(node a,node b) {return a.b<b.b;}

struct seg

{

    int l,r;

}c[N];

bool operator < (seg a,seg b) {return a.r==b.r?a.l<b.l:a.r<b.r;}

inline int read()

{

    char ch=getchar();int s=,f=;

    while (ch<''||ch>'') {if (ch=='-') f=-;ch=getchar();}

    while (ch>=''&&ch<='') {s=(s<<)+(s<<)+ch-'';ch=getchar();}

    return s*f;

}

ll f[N],s[N];

int main()

{

    freopen("river.in","r",stdin);

    freopen("river.out","w",stdout);

    n=read();

    for (int i=;i<=n;i++) p[i].b=read(),p[i].k=read();

    sort(p+,p++n,cmpk);

    for (int i=;i<=n;i++) p[i].id=i;

    sort(p+,p++n,cmpb);

    int mi=n;

    for (int i=n;i>=;i--) mi=min(mi,p[i].id),c[p[i].id].l=mi;

    int mx=;

    for (int i=;i<=n;i++) mx=max(mx,p[i].id),c[p[i].id].r=mx;

    sort(c+,c++n);

    int pos=;

    for (int i=;i<=n;i++)

    {

        while (pos<c[i].r-)

        {

            ++pos;

            s[pos]=(s[pos-]+f[pos])%mo;

        }

        (f[c[i].r]*=)%=mo;//这个区间可以选，也可以不选

        (f[c[i].r]+=s[c[i].r-]-(c[i].l>=?s[c[i].l-]:)+mo)%=mo;

        if (c[i].l==) (f[c[i].r]+=)%=mo;

    }

    printf("%lld\n",f[n]%mo);

    return ;

}