#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#define pb push_back
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " : " << x << '\n'
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef string str;
typedef pair<ll, ll> pll;
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
const ll Mod = 1000000007LL;
const int Maxn = 2e6 + 10;
const ll Inf = 2242545357980376863LL;
const ll Log = 30;
int T[Maxn], st[Maxn], fn[Maxn];
int seg[4 * Maxn];
void add(int id, int ind, int x, int L, int R){
if((ind < L) || (R <= ind)) return ;
if((ind == L) && (R == ind + 1)){
seg[id] = x;
return ;
}
int mid = (L + R) >> 1;
add(id << 1, ind, x, L, mid);
add(id << 1 | 1, ind, x, mid, R);
seg[id] = max(seg[id << 1], seg[id << 1 | 1]);
}
int get(int id, int l, int r, int L, int R){
if((r <= L) || (R <= l)) return -1;
if((l <= L) && (R <= r)) return seg[id];
int mid = (L + R) >> 1;
return max(get(id << 1, l, r, L, mid), get(id << 1 | 1, l, r, mid, R));
}
int seg2[4 * Maxn];
void add2(int id, int ind, int x, int L, int R){
if((ind < L) || (R <= ind)) return ;
if((ind == L) && (R == ind + 1)){
seg2[id] = x;
return ;
}
int mid = (L + R) >> 1;
add2(id << 1, ind, x, L, mid);
add2(id << 1 | 1, ind, x, mid, R);
seg2[id] = min(seg2[id << 1], seg2[id << 1 | 1]);
}
int get2(int id, int l, int r, int L, int R){
if((r <= L) || (R <= l)) return Maxn;
if((l <= L) && (R <= r)) return seg2[id];
int mid = (L + R) >> 1;
return min(get2(id << 1, l, r, L, mid), get2(id << 1 | 1, l, r, mid, R));
}
int mk[Maxn];
void DFS(int u, int c){
mk[u] = c;
add(1, st[u], -1, 0, Maxn);
add2(1, fn[u], Maxn, 0, Maxn);
int adj;
while( fn[u] < (adj = get(1, st[u], fn[u], 0, Maxn)) ) DFS(-T[adj], 2 - c);
while( st[u] > (adj = get2(1, st[u], fn[u], 0, Maxn)) ) DFS(T[adj], 2 - c);
}
stack<ll> A, B;
int main(){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
memset(seg, -1, sizeof seg);
memset(seg2, 31, sizeof seg2);
ll n;
cin >> n;
for(int i = 1; i <= n; i++){
cin >> st[i] >> fn[i];
T[st[i]] = i;
T[fn[i]] = -i;
add(1, st[i], fn[i], 0, Maxn);
add2(1, fn[i], st[i], 0, Maxn);
}
ll ans = 1;
for(int i = 1; i <= n; i++)
if(!mk[i]){
DFS(i, 1);
ans = (ans + ans) % Mod;
}
for(int i = 1; i <= n + n; i++){
if(T[i] > 0){
if(mk[T[i]] == 1) A.push(i);
else B.push(i);
} else {
if(mk[-T[i]] == 1){
if(A.empty() || A.top() != -T[i]) return cout << 0, 0;
else A.pop();
} else {
if(B.empty() || B.top() != -T[i]) return cout << 0, 0;
else B.pop();
}
}
}
cout << ans << '\n';
return 0;
}
