public static void Solve()
{
var N = Scanner.Scan <int>();
var M = 400000;
var dsu = new DisjointSetUnion(M);
var edge = new int[M];
for (var i = 0; i < N; i++)
{
var(a, b) = Scanner.Scan <int, int>();
var u = dsu.LeaderOf(a - 1);
var v = dsu.LeaderOf(b - 1);
var w = u;
if (!dsu.IsSame(u, v))
{
w = dsu.Merge(u, v);
edge[w] += edge[w == u ? v : u];
}
edge[w]++;
}
var answer = 0;
for (var i = 0; i < M; i++)
{
if (dsu.LeaderOf(i) == i)
{
answer += Math.Min(edge[i], dsu.SizeOf(i));
}
}
Console.WriteLine(answer);
}
public static void Solve()
{
var N = Scanner.Scan <int>();
var X = new int[N];
var Y = new int[N];
for (var i = 0; i < N; i++)
{
var(x, y) = Scanner.Scan <int, int>();
X[i] = x - 1;
Y[i] = y - 1;
}
var YByX = new int[N];
for (var i = 0; i < N; i++)
{
YByX[X[i]] = Y[i];
}
var indexes = new int[N];
for (var i = 0; i < N; i++)
{
indexes[X[i]] = i;
}
var comp = Comparer <(int y, int leader)> .Create((l, r) => Comparer <int> .Default.Compare(l.y, r.y));
var queue = new PriorityQueue <(int y, int leader)>(comp);
var dsu = new DisjointSetUnion(N);
for (var i = 0; i < N; i++)
{
var y = YByX[i];
var leader = i;
while (queue.Any() && queue.Peek().y < YByX[i])
{
var tmp = queue.Dequeue();
dsu.Merge(i, tmp.leader);
leader = dsu.LeaderOf(i);
y = Math.Min(y, tmp.y);
}
queue.Enqueue((y, leader));
}
var answer = new int[N];
for (var i = 0; i < N; i++)
{
answer[indexes[i]] = dsu.SizeOf(i);
}
for (var k = 0; k < N; k++)
{
Console.WriteLine(answer[k]);
}
}
public static void Solve()
{
var(N, M) = Scanner.Scan <int, int>();
var dsu = new DisjointSetUnion(N + M);
var used = new bool[M];
for (var i = 0; i < N; i++)
{
var L = Scanner.ScanEnumerable <int>().Skip(1).Select(x => x - 1).ToArray();
foreach (var l in L)
{
dsu.Merge(i, N + l);
used[l] = true;
}
}
var no = used.Count(x => !x);
var answer = dsu.SizeOf(0) == N + M - no;
Console.WriteLine(answer ? "YES" : "NO");
}