1 /*
2 找无向连通的割点
3 */
4
5 // include file
6 #include <cstdio>
7 #include <cstdlib>
8 #include <cstring>
9 #include <cmath>
10 #include <cctype>
11 #include <ctime>
12
13 #include <iostream>
14 #include <sstream>
15 #include <fstream>
16 #include <iomanip>
17 #include <bitset>
18
19 #include <algorithm>
20 #include <string>
21 #include <vector>
22 #include <queue>
23 #include <set>
24 #include <list>
25 #include <functional>
26
27 using namespace std;
28
29 // typedef
30 typedef long long LL;
31 typedef unsigned long long ULL;
32 typedef __int64 Bint;
33
34 //
35 #define read freopen("in.txt","r",stdin)
36 #define write freopen("out.txt","w",stdout)
37 #define FORi(a,b,c) for(int i=(a);i<(b);i+=c)
38 #define FORj(a,b,c) for(int j=(a);j<(b);j+=c)
39 #define FORk(a,b,c) for(int k=(a);k<(b);k+=c)
40 #define FORp(a,b,c) for(int p=(a);p<(b);p+=c)
41 #define FORii(a,b,c) for(int ii=(a);ii<(b);ii+=c)
42 #define FORjj(a,b,c) for(int jj=(a);jj<(b);jj+=c)
43 #define FORkk(a,b,c) for(int kk=(a);kk<(b);kk+=c)
44
45 #define FF(i,a) for(int i=0;i<(a);i++)
46 #define FFD(i,a) for(int i=(a)-1;i>=0;i--)
47
48 #define Z(a) (a<<1)
49 #define Y(a) (a>>1)
50
51 const double eps = 1e-6;
52 const double INFf = 1e10;
53 const int INFi = 1000000000;
54 const double Pi = acos(-1.0);
55
56 template<class T> inline T sqr(T a){return a*a;}
57 template<class T> inline T TMAX(T x,T y)
58 {
59 if(x>y) return x;
60 return y;
61 }
62 template<class T> inline T TMIN(T x,T y)
63 {
64 if(x<y) return x;
65 return y;
66 }
67 template<class T> inline void SWAP(T &x,T &y)
68 {
69 T t = x;
70 x = y;
71 y = t;
72 }
73 template<class T> inline T MMAX(T x,T y,T z)
74 {
75 return TMAX(TMAX(x,y),z);
76 }
77
78
79 // code begin
80 #define MAXN 110
81
82 int N;
83 struct node1
84 {
85 int e;
86 int next;
87 };
88 struct node2
89 {
90 int next;
91 };
92 node1 mem[MAXN*MAXN];
93 node2 G[MAXN];
94 int dfn[MAXN];
95 int low[MAXN];
96 int cut[MAXN];
97 int used[MAXN];
98 int cnt;
99
100 void Add_edge(int dx,int a,int b)
101 {
102 mem[dx].e = b;
103 mem[dx].next = G[a].next;
104 G[a].next = dx;
105 }
106
107 void BCC_tarjan(int i,int fa)
108 {
109 dfn[i] = cnt;
110 low[i] = cnt;
111 cnt++;
112 used[i] = true;
113 int son = 0;
114 int dx = G[i].next;
115 while(dx!=-1)
116 {
117 int v = mem[dx].e;
118 if(!used[v])
119 {
120 BCC_tarjan(v,i);
121 low[i] = TMIN(low[i],low[v]);
122 if(fa==-1) son++;
123 else if(low[v]>=dfn[i])
124 {
125 cut[i] = true;
126 }
127 }
128 else if(v!=fa)
129 {
130 low[i] = TMIN(low[i],dfn[v]);
131 }
132
133 dx = mem[dx].next;
134 }
135 if(fa==-1&&son>1) cut[i] = true;
136 }
137
138 void check()
139 {
140 printf("N:%d\n",N);
141 FORi(1,N+1,1)
142 {
143 printf("%d: ",i);
144 int dx = G[i].next;
145 while(dx!=-1)
146 {
147 printf(" %d",mem[dx].e);
148 dx = mem[dx].next;
149 }
150 printf("\n");
151 }
152 }
153
154 int main()
155 {
156 read;
157 write;
158 int a,b,dx;
159 while(scanf("%d",&N)!=-1)
160 {
161 if(N==0) break;
162 //getchar();
163 FORi(1,N+1,1)
164 {
165 G[i].next = -1;
166 }
167 dx = 0;
168 while(scanf("%d",&a)!=-1)
169 {
170 if(a==0)
171 {
172 break;
173 }
174 while(getchar()!='\n')
175 {
176 scanf("%d",&b);
177 Add_edge(dx++,a,b);
178 Add_edge(dx++,b,a);
179 }
180 }
181
182
183 //check();
184
185 memset(used,0,sizeof(used));
186 memset(dfn,0,sizeof(dfn));
187 memset(low,0,sizeof(low));
188 memset(cut,0,sizeof(cut));
189 cnt = 1;
190 FORi(1,N+1,1)
191 {
192 if(!used[i])
193 {
194 BCC_tarjan(i,-1);
195 }
196 }
197
198 // 把所有的割点都标记好了
199 int ans = 0;
200 FORi(1,N+1,1)
201 {
202 if(cut[i])
203 ans++;
204 }
205 printf("%d\n",ans);
206 }
207 return 0;
208 }
