http://acm.hdu.edu.cn/showproblem.php?pid=1054

题意：保卫城市，给一棵树，让求放几个士兵，可以看到所有的树的节点；

题解：

最小点覆盖数

二分匹配vecter建图，最大匹配的值除以2就是答案；

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
#define endl "\n"
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=1500+10;
const int M=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,p,l,r,u,v;
int ans,cnt,flag,temp,sum;
int mp[N][N];
int col[N];
bool vis[N];
char str;
struct node{};
vector<int>G[N];
bool dfs(int u){
    for(int i=0,j=G[u].size();i<j;i++){
        int v=G[u][i];
        if(!vis[v]){
            vis[v]=1;
            if(col[v]==-1||dfs(col[v])){
                col[v]=u;
                return 1;
            }
        }
    }
    return 0;
}
int maxmatch(){
    int res=0;
    for(int i=0;i<n;i++){
        memset(vis,0,sizeof(vis));
        if(dfs(i))res++;
    }
    return res;
}
void init(){
    memset(mp,0,sizeof(mp));
    memset(col,-1,sizeof(col));
    for(int i=0;i<n;i++)
        G[i].clear();
    ans=0;
}
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    //ios::sync_with_stdio(false);
    //cin.tie(0);
    //cout.tie(0);
    //scanf("%d",&t);
    while(~scanf("%d",&n)){
        //scanf("%d%d",&n,&m);
        init();
        for(int i=1;i<=n;i++){
            scanf("%d:(%d)",&u,&k);
            for(int j=1;j<=k;j++){
                scanf("%d",&v);
                //mp[u][v]=1;
                //mp[v][u]=1;
                G[u].push_back(v);
                G[v].push_back(u);
            }
        }
        cout<<maxmatch()/2<<endl;
    }

#ifdef DEBUG
	printf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC);
#endif
    //cout << "Hello world!" << endl;
    return 0;
}