#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pair<int,int>> vpi;
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)
#define pb push_back
#define rsz resize
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
#define fi first
#define se second
// subtask 1
int const N=5e2+3;
int a[N],b[N];
int const D=1e6+3;
ll dp[D];
ll mod =1e9+7;
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
int n;
cin>>n;
set<int> st;
F0R(i,n)
{
cin>>a[i]>>b[i];
FOR(j,a[i],b[i]+1)
{
st.insert(j);
}
}
vi v(all(st));
map<int,int>mp;
F0R(i,sz(st))
{
mp[v[i]]=i+1;
}
F0R(i,n)
{
a[i]=mp[a[i]];
b[i]=mp[b[i]];
}
F0R(j,sz(st)+1)
{
dp[j]=0;
}
dp[0]=1;
F0R(i,n)
{
ll sum=0;
F0R(j,b[i]+1)
{
ll temp = dp[j];
if(j>=a[i])
{
dp[j]+=sum;
dp[j]%=mod;
}
sum += temp;
sum%=mod;
}
}
ll ans=0;
FOR(j,1,sz(st)+1)
{
ans+=dp[j];
ans%=mod;
}
cout<<ans<<'\n';
return 0;
}
