#include<bits/stdc++.h>
#define god dimasi5eks
#pragma GCC optimize("O3")
#define fi first
#define se second
#define pb push_back
#define pf push_front
#define mod 1000000007
#define dancila 3.14159265359
#define eps 1e-9
// #define fisier 1
using namespace std;
typedef long long ll;
int add(int a, int b)
{
int x = a+b;
if(x >= mod)
x -= mod;
if(x < 0)
x += mod;
return x;
}
ll mul(ll a, ll b)
{
return (a*b) % mod;
}
ll pw(ll a, ll b)
{
ll ans = 1;
while(b)
{
if(b & 1)
ans = (ans * a) % mod;
a = (a * a) % mod;
b >>= 1;
}
return ans;
}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
long long rand_seed()
{
long long a = rng();
return a;
}
pair<int, int> bk[1000002];
int n, ways;
int main()
{
#ifdef fisier
ifstream f("input.in");
ofstream g("output.out");
#endif
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
for(int i = 0; i < n; ++i)
cin >> bk[i].fi >> bk[i].se;
sort(bk, bk + n);
for(int i = 0; i < (1<<n); ++i)
{
vector<int> v[3];
bool valid = 1;
for(int j = 0; j < n; ++j)
{
while(!v[1].empty() && v[1].back() < bk[j].fi)
v[1].pop_back();
while(!v[2].empty() && v[2].back() < bk[j].fi)
v[2].pop_back();
if(i & (1<<j))
{
if(v[1].empty() || v[1].back() > bk[j].se)
v[1].pb(bk[j].se);
else
{
valid = 0;
break;
}
}
else
{
if(v[2].empty() || v[2].back() > bk[j].se)
v[2].pb(bk[j].se);
else
{
valid = 0;
break;
}
}
}
ways += valid;
}
int p2 = 1;
while(p2 < ways)
p2 *= 2;
assert(ways == 0 || p2 == ways);
cout << ways;
return 0;
}
