import ac_library.DSU
import java.io.BufferedInputStream
import java.io.StreamTokenizer

fun main() {
    val st = StreamTokenizer(BufferedInputStream(System.`in`))
    fun ni(): Int {
        st.nextToken()
        return st.nval.toInt()
    }
    val n = ni()
    val m = ni()
    val d = DSU(n)
    repeat(m) {
        val u = ni()
        val v = ni()
        d.merge(u, v)
    }
    var c = 0
    for (i in 0 until n) if (d.leader(i) == i) c++
    println(c)
}