#include<bits/stdc++.h>
#define int long long
#define dd second
#define mp make_pair
#define pb push_back
#define ff first
#define dd second
#define pp pair<int,int>
#define maxx 200005
using namespace std;
int n;
int mod = 1e9+7;
int ans = 1;
vector<int> graph[maxx];
vector<int> graph2[maxx];
vector<int> kol;
int ozn[maxx];
int bylem[maxx];

void dfs(int i)
{
    bylem[i] = 1;
    for(auto &x:graph[i])
    {
        if(bylem[x] == 1)
        {
            ozn[i] = 1;
        }
        if(bylem[x] == 0)
        {
            dfs(x);
        }
        if(ozn[x]) ozn[i] = 1;
    }
    bylem[i] = 2;
    kol.pb(i);
}

void dfs3(int i)
{
    bylem[i] = 1;
    for(auto &x:graph2[i])
    {
        if(bylem[x] == 0)
        {
            dfs3(x);
        }
    }
    kol.pb(i);
}

int dfs2(int i)
{
    bylem[i] = 1;
    int res = 1;
    for(auto &x:graph2[i])
    {
        if(bylem[x] == 0) res += dfs2(x);
    }
    return res;
}

int dfs4(int i)
{
    //cout << i <<  " " << graph2[i].size() << endl;
    int res = 1;
    bylem[i] = 1;
    for(int x : graph2[i])
    {
        if(bylem[x] == 0 and ozn[x] == 0) res += dfs4(x);
    }
    return res;
}

main()
{
    ios_base::sync_with_stdio(false);
    cin >> n;
    for(int i = 0; i < maxx; ++i) bylem[i] = ozn[i] =0;
    for(int i = 0; i < n; ++i)
    {
        int a,b; cin >> a >> b;
        if(a != b)graph[a].pb(b); if(a != b)graph2[b].pb(a);
    }
    for(int i = 1; i <=2*n; ++i)
    {
        if(bylem[i] == 0)
        {
            dfs(i);
        }
    }
    reverse(kol.begin(), kol.end());
    for(int i = 0; i < maxx; ++i) bylem[i] = 0;
    for(int i:kol)
    {
        if(bylem[i] == 0)
        {
            int wyn = dfs2(i);
           // cout << i << " " << wyn << endl;
            if(wyn > 1) {ans *= 2; ans %= mod;}
        }
    }
    for(int i = 0; i < maxx; ++i) bylem[i] = 0;
    kol.resize(0);
    for(int i = 1; i <=2*n; ++i)
    {
        if(bylem[i] == 0)
        {
            dfs3(i);
        }
    }
    reverse(kol.begin(), kol.end());
    for(int i = 0; i < maxx; ++i) bylem[i] = 0;
    for(int i : kol)
    {
        if(bylem[i] == 0 and ozn[i] == 0)
        {
            int temp = dfs4(i);
            //cout << i << " " << temp <<  " 2 " << endl;
            if(temp > 1) {ans *= temp; ans %= mod;}
        }
    }

    cout << ans << endl;
}