var input = require("fs").readFileSync("/dev/stdin", "utf8").trim().split("\n");
var obj = {
  "list" : input,
  "index" : 0,
  "max" : input.length,
  "next" : function(){
    if(!this.hasNext()){throw "NoSuchElementException:次に要素は無いよ";}
    var returnObj = this.list[this.index];
    this.index++;
    return returnObj;
  },
  "hasNext" : function(){return (this.index < this.max);}
}
Main();
function next(){return obj.next();}
function hasNext(){return obj.hasNext();}
function myout(t){console.log(t);}//standard output
function myerr(t){console.error(t);}//standard error
//[no]要素の扱い。数値型
//不明値、異常時:引数そのまま返す
//1:数値へ変換 2:半角SPで分割 4:半角SPで分割し、数値配列へ
//6:1文字に分割 7:1文字に分割し、数値配列へ
//8:半角SPで結合 9:改行で結合 0:文字なしで結合
function myconv(i,no){try{switch(no){case 1:return parseInt(i);case 2:return i.split(" ");case 4:return i.split(" ").map((a)=>Number(a));case 6:return i.split("");case 7:return i.split("").map((a)=>Number(a));case 8:return i.join(" ");case 9:return i.join("\n");case 0:return i.join("");default:return i;}}catch(e){return i;}}
function Main() {
  var one = myconv(next(),4);
  var N = one[0];
  var M = one[1];
  var list = new Array(N);
  for(var i = 0; i < N; i++){
    list[i] = {
    	"child" : [],
        "visit" : false
    };
  }
  for(var i = 0; i < M; i++){
    var tmp = myconv(next(),4);
    list[tmp[0]-1].child.push(tmp[1]-1);
    list[tmp[1]-1].child.push(tmp[0]-1);
  }
  var count = 0;
  
  for(var i = 0; i < N; i++){
    if(!list[i]["visit"]){
      count++;
      var queue = [list[i]];
      while(queue.length > 0){
        var tmpQueue = queue.shift();
        tmpQueue["visit"] = true;
        var children = tmpQueue["child"];
        for(var j = 0; j < children.length; j++){
          if(list[children[j]]["visit"]){continue;}
           queue.push(list[children[j]]);
        }
      }
    }
  }
  /*function dfs(parent){
    list[parent]["visit"] = true;
    var children = list[parent]["child"];
    //myout(parent +" : "+children);
    for(var i = 0; i < children.length; i++){
      if(list[children[i]]["visit"]){continue;}
      if(children[i] == parent){continue;}
      dfs(children[i]);
    }
  }*/
  
  myout(count);
}