1 #include<cstdio>
  2 #include<cstring>
  3 const int N=100+5;
  4 const int INF=0x3f3f3f3f;
  5 struct EDGE{
  6     int v,w,next;
  7 }edge[N*N],edge2[N*N];
  8 int g;
  9 int first[N],numh[N],h[N],curedge[N],pre[N];
 10 //int first[N],gap[N],pre[N],dis[N],cur[N];
 11 int min(int a,int b)
 12 {
 13     return a<b?a:b;
 14 }
 15 void AddEdge(int u,int v,int w)
 16 {
 17     edge[g].v=v;
 18     edge[g].w=w;
 19     edge[g].next=first[u];
 20     first[u]=g++;
 21     edge[g].v=u;       //反向边
 22     edge[g].w=0;
 23     edge[g].next=first[v];
 24     first[v]=g++;
 25 }
 26 int sap(int s,int t,int n,EDGE edge[])
 27 {
 28     int cur_flow,u,tmp,neck,i;
 29     int flow_ans=0;
 30     memset(h,0,sizeof(h));
 31     memset(numh,0,sizeof(numh));
 32     memset(pre,-1,sizeof(pre));
 33     for(i=0;i<n;i++)
 34         curedge[i]=first[i];
 35     numh[0]=n;
 36     u=s;
 37     while(h[s]<n)
 38     {
 39         if(u==t)
 40         {
 41             cur_flow=INF+1;     //注意：要+1
 42             for(i=s;i!=t;i=edge[curedge[i]].v)
 43             {
 44                 if(cur_flow>edge[curedge[i]].w)
 45                 {
 46                     neck=i;
 47                     cur_flow=edge[curedge[i]].w;
 48                 }
 49             }
 50             for(i=s;i!=t;i=edge[curedge[i]].v)
 51             {
 52                 tmp=curedge[i];
 53                 edge[tmp].w-=cur_flow;
 54                 edge[tmp^1].w+=cur_flow;
 55             }
 56             flow_ans+=cur_flow;
 57             u=neck;
 58         }
 59         for(i=curedge[u];i!=-1;i=edge[i].next)
 60         {
 61             if(edge[i].w&&h[u]==h[edge[i].v]+1)
 62                 break;
 63         }
 64         if(i!=-1)
 65         {
 66             curedge[u]=i;
 67             pre[edge[i].v]=u;
 68             u=edge[i].v;
 69         }
 70         else
 71         {
 72             if(0==--numh[h[u]])
 73                 break;
 74             curedge[u]=first[u];
 75             for(tmp=n,i=first[u];i!=-1;i=edge[i].next)
 76             {
 77                 if(edge[i].w)
 78                     tmp=min(tmp,h[edge[i].v]);
 79             }
 80             h[u]=tmp+1;
 81             numh[h[u]]++;
 82             if(u!=s)
 83                 u=pre[u];
 84         }
 85     }
 86     return flow_ans;
 87 }
 88 /*int cou;
 89 int sap(int s,int t,int n,EDGE edge[])
 90 {
 91     memset(cur,0,sizeof(cur));
 92     memset(pre,0,sizeof(pre));
 93     int flow=0,i;
 94     int u=pre[s]=s;
 95     cou=n;
 96     for(i=0;i<cou;i++)
 97     {
 98         cur[i]=first[i];
 99         dis[i]=gap[i]=0;
100     }
101     gap[0]=cou;
102     int aug=INF;
103     while(dis[s]<cou)
104     {
105         bool flag=true;
106         for(int j=cur[u];j!=-1;j=cur[u]=edge[j].next){
107             int v=edge[j].v;
108             if(edge[j].w>0&&dis[u]==dis[v]+1)
109             {
110                 flag=false;
111                 pre[v]=u;
112                 u=v;
113                 if(aug>edge[j].w)
114                     aug=edge[j].w;
115                 if(u==t)
116                 {
117                     flow+=aug;
118                     while(u!=s){
119                         u=pre[u];
120                         edge[cur[u]].w-=aug;
121                         edge[cur[u]^1].w+=aug;
122                     }
123                     aug=INF;
124                 }
125                 break;
126             }
127         }
128         if(!flag)
129             continue;
130         int minh=cou;
131         for(int k=first[u];k!=-1;k=edge[k].next)
132         {
133             int v=edge[k].v;
134             if(edge[k].w>0&&minh>dis[v]){
135                 minh=dis[v];
136                 cur[u]=k;
137             }
138         }
139         if((--gap[dis[u]])==0)
140             break;
141         gap[dis[u]=minh+1]++;
142         u=pre[u];
143     }
144     return flow;
145 }*/
146 int main()
147 {
148 //    printf("%d\n",INF);
149     int i,n,m,u,v,k;
150     while(scanf("%d%d",&n,&m)!=EOF)
151     {
152         if(m==0)
153         {
154             if(n==1)
155                 printf("1\n");
156             else
157                 printf("0\n");
158             continue;
159         }
160         g=0;
161         memset(first,-1,sizeof(first));
162         for(i=0;i<n;i++)
163             AddEdge(i,i+n,1);
164         for(i=0;i<m;i++)
165         {
166             scanf(" (%d,%d)",&u,&v);
167             AddEdge(u+n,v,INF);
168             AddEdge(v+n,u,INF);
169         }
170         int ans=INF;
171         for(i=1;i<n;i++)
172         {
173             for(k=0;k<g;k++)
174                 edge2[k]=edge[k];
175             ans=min(ans,sap(0+n,i,n*2,edge2));
176         }
177         if(ans==INF)
178             ans=n;
179         printf("%d\n",ans);
180     }
181     return 0;
182 }