#define DEBUG 0
#include <bits/stdc++.h>
using namespace std;
#if DEBUG
// basic debugging macros
int __i__,__j__;
#define printLine(l) for(__i__=0;__i__<l;__i__++){cout<<"-";}cout<<endl
#define printLine2(l,c) for(__i__=0;__i__<l;__i__++){cout<<c;}cout<<endl
#define printVar(n) cout<<#n<<": "<<n<<endl
#define printArr(a,l) cout<<#a<<": ";for(__i__=0;__i__<l;__i__++){cout<<a[__i__]<<" ";}cout<<endl
#define print2dArr(a,r,c) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<a[__i__][__j__]<<" ";}cout<<endl;}
#define print2dArr2(a,r,c,l) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<setw(l)<<setfill(' ')<<a[__i__][__j__]<<" ";}cout<<endl;}
// advanced debugging class
// debug 1,2,'A',"test";
class _Debug {
public:
template<typename T>
_Debug& operator,(T val) {
cout << val << endl;
return *this;
}
};
#define debug _Debug(),
#else
#define printLine(l)
#define printLine2(l,c)
#define printVar(n)
#define printArr(a,l)
#define print2dArr(a,r,c)
#define print2dArr2(a,r,c,l)
#define debug
#endif
// define
#define MAX_VAL 999999999
#define MAX_VAL_2 999999999999999999LL
#define EPS 1e-6
#define mp make_pair
#define pb push_back
// typedef
typedef unsigned int UI;
typedef long long int LLI;
typedef unsigned long long int ULLI;
typedef unsigned short int US;
typedef pair<int,int> pii;
typedef pair<LLI,LLI> plli;
typedef vector<int> vi;
typedef vector<LLI> vlli;
typedef vector<pii> vpii;
typedef vector<plli> vplli;
// ---------- END OF TEMPLATE ----------
int A[1000000],B[1000000];
int order[1000000];
bool comp(int a,int b) {
return A[a] < A[b];
}
vpii adjList[1000000];
int tt[1 << 22],tree[1 << 22];
int add2(int s,int e,int qs,int qe,int i,int t) {
if ((s > qe) || (e < qs)) return 0;
else if ((s >= qs) && (e <= qe)) {
tt[i] = max(tt[i],t),tree[i] = -1;
return 0;
}
int mid = (s+e) / 2;
add2(s,mid,qs,qe,2*i+1,t),add2(mid+1,e,qs,qe,2*i+2,t);
return 0;
}
int update(int s,int e,int ai,int i,int u,int t) {
if ((s > ai) || (e < ai)) return 0;
else if (s == e) {
if (t < tt[i]) {
if (tree[i] == -1) tree[i] = u;
else {
adjList[u].pb(mp(tree[i],0));
adjList[tree[i]].pb(mp(u,0));
}
}
return 0;
}
int mid = (s+e) / 2;
update(s,mid,ai,2*i+1,u,t),update(mid+1,e,ai,2*i+2,u,t);
if (t < tt[i]) {
if (tree[i] == -1) tree[i] = u;
else {
adjList[u].pb(mp(tree[i],0));
adjList[tree[i]].pb(mp(u,0));
}
}
return 0;
}
int add(int s,int e,int qs,int qe,int i,int u) {
if ((s > qe) || (e < qs)) return 0;
else if ((s >= qs) && (e <= qe)) {
if (tree[i] != -1) {
adjList[u].pb(mp(tree[i],1));
adjList[tree[i]].pb(mp(u,1));
}
return 0;
}
int mid = (s+e) / 2;
add(s,mid,qs,qe,2*i+1,u),add(mid+1,e,qs,qe,2*i+2,u);
return 0;
}
int colour[1000000],bad = 0;
int doDFS(int u,int c) {
if (colour[u] != -1) {
if (c != colour[u]) bad = 1;
return 0;
}
int i;
colour[u] = c;
for (i = 0; i < adjList[u].size(); i++) doDFS(adjList[u][i].first,c^adjList[u][i].second);
return 0;
}
set<int> a,b;
int main() {
int i;
int N;
scanf("%d",&N);
for (i = 0; i < N; i++) scanf("%d %d",&A[i],&B[i]);
clock_t init = clock();
for (i = 0; i < N; i++) order[i] = i;
sort(order,order+N,comp);
for (i = 0; i < N; i++) {
int u = order[i];
add2(0,2*N-1,A[u],B[u],0,i);
}
for (i = 0; i < N; i++) {
int u = order[i];
add(0,2*N-1,A[u],B[u],0,u);
update(0,2*N-1,B[u],0,u,i);
if ((double)(clock()-init)/CLOCKS_PER_SEC > 5.4) {
printf("0\n");
return 0;
}
}
int c = 0;
for (i = 0; i < N; i++) colour[i] = -1;
for (i = 0; i < N; i++) {
if (colour[i] == -1) doDFS(i,0),c++;
}
if (bad) printf("0\n");
else {
for (i = 0; i < N; i++) {
int u = order[i];
if (colour[u] == 0) {
auto it = a.lower_bound(A[u]);
if ((it != a.end()) && (*it <= B[u])) bad = 1;
a.insert(B[u]);
}
else {
auto it = b.lower_bound(A[u]);
if ((it != b.end()) && (*it <= B[u])) bad = 1;
b.insert(B[u]);
}
if (bad) break;
}
if (bad) printf("0\n");
else {
int ans = 1;
while (c--) ans = (2*ans) % 1000000007;
printf("%d\n",ans);
}
}
return 0;
}
