LA 3644 X-Plosives

#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <vector>
#include <deque>
#include <list>
#include <cctype>
#include <algorithm>
#include <climits>
#include <queue>
#include <stack>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <cstdlib>
#include <ctime>
#define ll long long
#define ull unsigned long long
#define all(x) (x).begin(), (x).end()
#define clr(a, v) memset( a , v , sizeof(a) )
#define pb push_back
#define mp make_pair
#define read(f) freopen(f, "r", stdin)
#define write(f) freopen(f, "w", stdout)
using namespace std;

int num[100005];

int find ( int x )
{
return x == num[x] ? x : num[x] = find( num[x] );
}

int main()
{
ios::sync_with_stdio( false );
int a, b;
while ( cin >> a )
{
for ( int i = 0; i < 100005; i ++ )
num[i] = i;
int k = 0;
int cnt = 0;
for ( ; a != -1; )
{
cin >> b;
a = find ( a );
b = find ( b );
if ( a == b )
{
cnt ++;
}
else
{
num[a] = b;
}
cin >> a;
}
cout << cnt << endl;
}
return 0;
}