#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int maxn = 2e6+6, M = 1e9+7;
int N;
pair<int,int> invl[maxn];
int color[maxn]; //0 = unset, 1, 2
int at[maxn];
struct Line
{
int se, en;
} lines[maxn];
int start[4*maxn], endd[4*maxn], val[4*maxn];
void build(int i, int l, int r) {
start[i] = l;
endd[i] = r;
if (l == r) {
return;
}
int m = (l+r)/2;
build(i*2,l,m);
build(i*2+1,m+1,r);
}
int update(int a, int b) {
if (a == -1 || b == -1) return -1;
if (a == 0) return b;
if (b == 0) return a;
if (a == b) return a;
assert((a == 1 && b == 2) || (a == 2 && b == 1));
/*
if (!((a == 1 && b == 2) || (a == 2 && b == 1))) {
cout << a << ' ' << b << endl;
exit(0);
}
*/
return -1;
}
void sset(int i, int idx, int x) {
if (start[i] == idx && endd[i] == idx) {
val[i] = x;
return;
}
if (idx <= (start[i]+endd[i])/2)
sset(i*2,idx,x);
else
sset(i*2+1,idx,x);
val[i] = update(val[i*2],val[i*2+1]);
}
int getColor(int i, int l, int r) {
if (l <= start[i] && endd[i] <= r) {
return val[i];
}
int m = (start[i]+endd[i])/2;
int res = 0;
if (l <= m) res = update(res,getColor(i*2,l,r));
if (r > m) res = update(res,getColor(i*2+1,l,r));
return res;
}
int main()
{
cin >> N;
for (int i = 1; i <= N; i++) {
int a, b; cin >> a >> b;
lines[i] = {a,b};
at[a] = i;
at[b] = -i;
//+ means start, - means end
}
//Keep an "active" set of lines in a segment tree by their
//endpoint.
build(1,1,2*N);
int currCount = 0;
int components = 0;
bool fail = false;
for (int i = 1; i <= 2*N; i++) {
bool isStart = at[i] > 0;
int id = abs(at[i]);
int se = lines[id].se;
int en = lines[id].en;
if (isStart) {
int c = getColor(1,se,en);
if (c == -1) {
fail = true;
break;
}
else if (c == 0) {
components++;
sset(1,en,1);
}
else {
assert(c == 1 || c == 2);
int d = c == 1 ? 2 : 1;
sset(1,en,d);
}
currCount++;
}
else {
//remove from set
sset(1,en,0);
currCount--;
}
}
if (fail) {
cout << "0\n";
}
else {
int ans = 1;
//printf("# comp = %d\n",components);
while (components--) {
ans = (1LL*ans*2) % M;
}
cout << ans << '\n';
}
}
