1 #include <iostream>
2 #include <algorithm>
3 using namespace std;
4 const int maxn = 100000 + 10;
5 int fa[maxn];
6
7 int Find(int x){
8 if (x == fa[x])
9 return x;
10 else
11 return fa[x] = Find(fa[x]);
12 }
13
14 int main(){
15 int a, b;
16 while (cin >> a){
17
18 //init
19 for (int i = 0; i < maxn; i++)
20 fa[i] = i;
21 int ans = 0;
22 while (a != -1){
23 cin >> b;
24 a = Find(a);
25 b = Find(b);
26 if (a == b)
27 ans++;
28 else
29 fa[b] = a;
30 cin >> a;
31 }
32 cout << ans << endl;
33 }
34 //system("pause");
35 return 0;
36 }
