UVA 1160

#include <bits/stdc++.h>

using namespace std;


class UF{

public:
    int *a, *sz;
    int n;

    UF(int n){
        sz = new int[n];
        a = new int[n];
        this->n = n;

        for(int i =0 ; i < n; i++)
            a[i] = i, sz[i] = 1;
    }

    ~UF(){
        delete sz;
        delete a;
    }

    int root(int p){
        while(a[p] != p) {
            a[p] = a[a[p]];
            p = a[p];
        }
        return p;
    }

    void merge(int p, int q){
        int i = root(p);
        int j = root(q);

        if(i == j) return;

        if(sz[i] > sz[j]) a[j] = i, sz[i] += sz[j];
        else a[i] = j, sz[j] += sz[i];
    }

    bool find(int p, int q){
        return root(p) == root(q);
    }

};

int main(){
    //ios_base::sync_with_stdio(false);
    //cin.tie(NULL);

    int x,y;
    UF *uf = new UF(100001);
    int total = 0;

    while(cin >> x){
        if(x == -1){
            cout << total << endl;
            total = 0;
            delete uf;
            uf = new UF(100001);
            continue;
        }

        cin >> y;

        if(uf->find(x,y)) total++;
        else{
            uf->merge(x,y);
        }
    }

    return 0;
}