//code by byf and lmj
#include <bits/stdc++.h>

#define MAXN 2000005

using namespace std;

int n,tot=,match[MAXN],head[MAXN];

bool visited[MAXN];

struct edge

{

    int to,nxt;

} e[MAXN << ];

template <typename T> inline void read(T &x)

{

    int f = ; x = ;

    char c = getchar();

    for (; !isdigit(c); c = getchar())

    {

        if (c == '-') f = -f;

    }

    for (; isdigit(c); c = getchar()) x = (x << ) + (x << ) + c - '';

    x *= f;

}

inline void addedge(int u,int v)

{

    tot++;

    e[tot] = (edge){v,head[u]};

    head[u] = tot;

}

inline bool hungary(int u)

{

    int v;

    visited[u] = true;

    for (register int i = head[u]; i; i = e[i].nxt)

    {

        v = e[i].to;

        if (!visited[v])

        {

            visited[v] = true;

            if (!match[v] || hungary(match[v]))

            {

                match[v] = u;

                return true;

            }

        }

    }

    return false;

}

int main() {

    read(n);

    for (register int i = ; i <= n; ++i)

    {

        int a,b;

        read(a); read(b);

        addedge(a,i+n); addedge(b,i+n);

    }

    if (n <= 5E4)

    {

        for (register int i = ; i <= n; ++i)

        {

            memset(visited,false,sizeof(visited));

            if (!hungary(i))

            {

                cout << i -  << endl;

                return ;

            }

        }

        cout << n << endl;

        return ;

    }

    for (register int i = ; i <= ; ++i)

    {

        for (register int j = ; j <= ; ++j) visited[j] = false;

        if (!hungary(i))

        {

            cout << i -  << endl;

            return ;

        }

    }

    cout << n << endl;

    return ;

}