uva 1160

 1 #include<cstdio>
 2 #define maxn 100005
 3 using namespace std;
 4 int f[maxn];
 5 int find(int x){return x==f[x]?x:f[x]=find(f[x]);}
 6 int main()
 7 {
 8     int x,y;
 9     while(scanf("%d",&x)!=EOF)
10     {
11         for(int i=0;i<maxn;i++)f[i]=i;
12         int cnt=0;
13         while(x!=-1)
14         {
15             scanf("%d",&y);
16             x=find(x),y=find(y);
17             if(x==y)cnt++;
18             else f[x]=y;
19             scanf("%d",&x);
20         }
21         printf("%d
",cnt);
22     }
23     return 0;
24 }