import atcoder/dsu
import std/strutils

let f = stdin.readAll().splitWhitespace()
let n = f[0].parseInt
let m = f[1].parseInt
var d = initDsu(n)
for i in 0 ..< m:
  discard d.merge(f[2 + 2 * i].parseInt, f[3 + 2 * i].parseInt)
var c = 0
for i in 0 ..< n:
  if d.leader(i) == i: inc c
echo c