#include <iostream>

 #include <cstdio>

 #include <climits>

 #include <cstring>

 #include <cstdlib>

 #include <cmath>

 #include <vector>

 #include <queue>

 #include <algorithm>

 #define esp 1e-6

 #define pb push_back

 #define in  freopen("in.txt", "r", stdin);

 #define out freopen("out.txt", "w", stdout);

 #define print(a) printf("%d\n",(a));

 #define bug puts("********))))))");

 #define Rep(i, c) for(__typeof(c.end()) i = c.begin(); i != c.end(); i++)

 #define inf 0x0f0f0f0f

 using namespace std;

 typedef long long  LL;

 typedef vector<int> VI;

 typedef pair<int, int> pii;

 typedef vector<pii,int> VII;

 typedef vector<int>:: iterator IT;

 #define N (int)(1e5+100)

 int pa[N], rank[N];

 void init(void)

 {

     for(int i = ; i < N; i++)

         pa[i] = i;

     memset(rank, , sizeof(rank));

 }

 void merge(int x, int y)

 {

     if(rank[x] > rank[y])

         pa[y] = x;

     else {

         pa[x] = y;

         if(rank[x] == rank[y])

             rank[y]++;

     }

 }

 int findset(int x)

 {

     return  (pa[x] == x) ? x: pa[x] = findset(pa[x]);

 }

 int main(void)

 {

 int x, y;

     while(~scanf("%d", &x))

     {

         int cnt = ;

         init();

         while(x != -)

         {

             scanf("%d", &y);

             x = findset(x), y = findset(y);

             if(x == y)

                 cnt++;

                 else merge(x, y);

             scanf("%d", &x);

         }

         printf("%d\n", cnt);

     }

     return ;

 }