1160.cpp

/**
 *                                   ____
 *       ____ ___  ____ ________  __/ __/
 *      / __ `__ \/ __ `/ ___/ / / / /_
 *     / / / / / / /_/ / /  / /_/ / __/
 *    /_/ /_/ /_/\__,_/_/   \__,_/_/
 *
 *    @link : https://the-redback.com
 */
#include <bits/stdc++.h>
using namespace std;

#define inf       10000000
#define mem(a, b) memset(a, b, sizeof(a))
#define NN        100010
int prnt[NN + 7];
struct data {
    int u, v;
};
vector<data> e;

int root(int n) {
    if (prnt[n] == n) return n;
    return root(prnt[n]);
}

int mst(int n) {
    int i, j, k, node, dist;
    for (i = 0; i <= n; i++) prnt[i] = i;
    node = dist = 0;
    for (i = 0; i < e.size() && node < n - 1; i++) {
        int u = root(e[i].v);
        int v = root(e[i].u);
        if (u != v)
            prnt[u] = v;
        else
            node++;
    }
    return node;
}

int main() {
    // freopen("C:\\Users\\Maruf Tuhin\\Desktop\\in.txt","r",stdin);
    // ios_base::sync_with_stdio(false);
    int i, j, k, l, n, r, c, u, v, w;
    int tc, t = 1, x = -1;
    data nn;
    // scanf("%d",&tc);
    while (~scanf("%d", &u)) {
        while (u != -1) {
            scanf("%d", &v);
            x = max(x, u);
            x = max(x, v);
            nn.u = u;
            nn.v = v;
            e.push_back(nn);
            scanf("%d", &u);
        }
        int ret = mst(x);
        printf("%d\n", ret);
        e.clear();
    }
    return 0;
}