const fs = require("fs");
const { DSU } = require("ac-library-js");

const data = fs.readFileSync(0, "utf8").split(/\s+/);
let p = 0;
const n = Number(data[p++]);
const m = Number(data[p++]);
const d = new DSU(n);
for (let i = 0; i < m; i++) {
  const u = Number(data[p++]);
  const v = Number(data[p++]);
  d.merge(u, v);
}
let c = 0;
for (let i = 0; i < n; i++) {
  if (d.leader(i) === i) c++;
}
console.log(c);