#include <bits/stdc++.h>
using namespace std;
#define sz(x) (int) (x).size()
#define all(x) (x).begin(), (x).end()
#define show(x) cerr << #x << " is " << x << endl;
#define show2(x,y) cerr << #x << " is " << x << " " << #y << " is " << y << endl;
#define show3(x,y,z) cerr << #x << " is " << x << " " << #y << " is " << y << " " << #z << " is " << z << endl;
#define tern(cond, a, b) (cond ? a : b)
#define l first
#define r second
typedef long long lint;
typedef pair<lint,lint> ii;
const lint mod = 1000000007;
int p[2000005];
int ans;
int findSet(int u){
if(p[u] == u) return u;
else return p[u] = findSet(p[u]);
}
bool unionSet(int u, int v){
u = findSet(u), v = findSet(v);
if(u == v) return false;
if(rand()&1) swap(u,v);
p[u] = v;
return true;
}
void merge(int a, int b){
if(unionSet(a*2, b*2+1)) ans--;
unionSet(a*2+1, b*2);
}
ii arr[4005];
int main(){
//freopen("i.txt","r",stdin);
ios_base::sync_with_stdio(false); cin.tie(0);
int n; cin >> n;
ans = n;
for(int i = 0;i < n;i++) cin >> arr[i].l >> arr[i].r;
for(int i = 0;i < 2*n;i++) p[i] = i;
for(int i = 0;i < n;i++){
for(int j = i+1;j < n;j++){
ii a = arr[i], b = arr[j];
if(a.l > b.l) swap(a,b);
if(a.l < b.l and b.l < a.r and a.r < b.r){
//show2(i,j);
merge(i,j);
}
}
}
for(int i = 0;i < n;i++){
if(findSet(i*2) == findSet(i*2+1)){
cout << 0;
return 0;
}
}
lint actlans = 1;
for(int i = 0;i < ans;i++){
actlans *= 2;
if(actlans >= mod) actlans -= mod;
}
cout << actlans;
}
