#include <iostream>

#include <cstring>

#include <cstdio>

#include <deque>

using namespace std;

const int maxn = ;

deque<int> p[maxn];  //树根到x的交错路径

bool adj[maxn][maxn];

int m[maxn]; //记录匹配情况

int d[maxn]; //记录奇点和偶点

int q[maxn], *qf, *qb; //记录可延伸的偶点

int n;

void label_one_side(int x, int y, int bi){

    for(int i = bi+; i < p[x].size(); i++){

        int z = p[x][i];

        if(d[z] == ){

            p[z] = p[y];

            p[z].insert(p[z].end(), p[x].rbegin(), p[x].rend()-i);

            d[z] = ;

            *qb++ = z;

        }

    }

}

bool BFS(int r){

    for(int i = ; i < n; i++) p[i].clear();

    p[r].push_back(r);

    for(int i = ; i < n; i++) d[i] = -;

    d[r] = ;

    qf = qb = q;

    *qb++ = r;

    while(qf < qb){

        for(int x = *qf++, y = ; y < n; y++){

            if(adj[x][y] && m[y] != y){

                if(d[y] == -){

                    if(m[y] == -){

                        for(int i = ; i+ < p[x].size(); i += ){

                            m[p[x][i]] = p[x][i+];

                            m[p[x][i+]] = p[x][i];

                        }

                        m[x] = y; m[y] = x;

                        return true;

                    } else {

                        int z = m[y];

                        p[z] = p[x];

                        p[z].push_back(y);

                        p[z].push_back(z);

                        d[y] = ; d[z] = ;

                        *qb++ = z;

                    }

                } else if(d[y] == ) {

                    int bi = ;

                    while(bi < p[x].size() && bi < p[y].size() && p[x][bi] == p[y][bi]) bi++;

                    bi--;

                    label_one_side(x, y, bi);

                    label_one_side(y, x, bi);

                }

            }

        }

    }

    return false;

}

int match(){

    for(int i = ; i < n; i++) m[i] = -;

    int c = ;

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

        if(m[i] == -)

            if(BFS(i)) c++;

            else m[i] = i;

    }

    return c;

}

int main(){

    cin>>n;

    int x, y;

    while(cin>>x>>y) adj[x][y] = adj[y][x] = true;

    match();

}

#include <iostream>

#include <cstring>

#include <cstdio>

using namespace std;

const int N = ;

int n;

bool adj[N][N];

int p[N];

int m[N];

int d[N];

int c1[N], c2[N];

int q[N], *qf, *qb;

int pp[N];

int f(int x) { return x == pp[x] ? x : pp[x] = f(pp[x]); }

void u(int x, int y) { pp[x] = y; }

int v[N];

void path(int r, int x){

    if(r == x) return;

    if(d[x] == ){

        path(r, p[p[x]]);

        int i = p[x], j = p[p[x]];

        m[i] = j; m[j] = i;

    } else if(d[x] == ){

        path(m[x], c1[x]);

        path(r, c2[x]);

        int i = c1[x], j = c2[x];

        m[i] = j; m[j] = i;

    }

}

int lca(int x, int y, int r){

    int i = f(x), j = f(y);

    while(i != j && v[i] !=  && v[j] != ){

        v[i] = ; v[j] = ;

        if(i != r) i = f(p[i]);

        if(j != r) j = f(p[j]);

    }

    int b = i, z = j; if(v[j] == ) swap(b, z);

    for(int i = b; i != z; i = f(p[i])) v[i] = -;

    v[z] = -;

    return b;

}

void contract_one_side(int x, int y, int b){

    for(int i = f(x); i != b; i = f(p[i])){

        u(i, b);

        if(d[i] == ) c1[i] = x, c2[i] = y, *qb++ = i;

    }

}

bool BFS(int r){

    for(int i = ; i < n; i++) pp[i] = i;

    for(int i = ; i < n; i++) v[i] = d[i] = -;

    d[r] = ;

    qf = qb = q;

    *qb++ = r;

    while(qf < qb){

        for(int x = *qf++, y = ; y < n; y++){

            if(!adj[x][y] || m[y] == y || f(x) == f(y)) continue;

            if(d[y] == -){

                if(m[y] == -){

                    path(r, x);

                    m[x] = y; m[y] = x;

                    return true;

                } else {

                    p[y] = x; p[m[y]] = y;

                    d[y] = ; d[m[y]] = ;

                    *qb++ = m[y];

                }

            } else if(d[f(y)] == ){

                int b = lca(x, y, r);

                contract_one_side(x, y, b);

                contract_one_side(y, x, b);

            }

        }

    }

    return false;

}

int main(){

}