Problem:
Score : 500 points

Problem Statement

There are N cards placed face down in a row. On each card, an integer 1 or 2 is written.

Let A_i be the integer written on the i-th card.

Your objective is to guess A_1, A_2, ..., A_N correctly.

You know the following facts:

For each i = 1, 2, ..., M, the value A_{X_i} + A_{Y_i} + Z_i is an even number.

You are a magician and can use the following magic any number of times:

Magic: Choose one card and know the integer A_i written on it. The cost of using this magic is 1.

What is the minimum cost required to determine all of A_1, A_2, ..., A_N?

It is guaranteed that there is no contradiction in given input.

Constraints

All values in input are integers.

2 \leq N \leq 10^5

1 \leq M \leq 10^5

1 \leq X_i < Y_i \leq N

1 \leq Z_i \leq 100

The pairs (X_i, Y_i) are distinct.

There is no contradiction in input. (That is, there exist integers A_1, A_2, ..., A_N that satisfy the conditions.)

Input

Input is given from Standard Input in the following format:

N M
X_1 Y_1 Z_1
X_2 Y_2 Z_2
\vdots
X_M Y_M Z_M

Output

Print the minimum total cost required to determine all of A_1, A_2, ..., A_N.

Sample Input 1

3 1
1 2 1

Sample Output 1

2

You can determine all of A_1, A_2, A_3 by using the magic for the first and third cards.

Sample Input 2

6 5
1 2 1
2 3 2
1 3 3
4 5 4
5 6 5

Sample Output 2

2

Sample Input 3

100000 1
1 100000 100

Sample Output 3

99999

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#include <algorithm>
#include <iostream>
#include <limits.h>
#include <math.h>
#include <queue>
#include <set>
#include <stdlib.h>
#include <string>
#include <vector>
#include <cstdio>
#include <iomanip>
#define ll long long
#define rep2(i,a,b) for(ll i=a;i<=b;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define rep3(i,a,b) for(ll i=a;i>=b;i--)
#define REP(e,v) for(auto e:v)
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pq priority_queue<int>
#define pqg priority_queue<int,vector<int>,greater<int>()>
#define pb push_back
#define vec vector<int>
#define vecvec vector<vector<int>>
#define vecll vector<ll>
#define vecvecll vector<vector<ll>>
#define bs binary_search
#define All(c) (c).begin(),(c).end()
#define mp make_pair
using namespace std;
int in(){int x;scanf("%d",&x);return x;}
string stin(){string s;cin>>s;return s;}
ll lin(){ll x;scanf("%lld",&x);return x;}
struct UnionFind{
    vec par,size;
    UnionFind(int n):par(n),size(n){
        rep(i,n){
            par[i]=i;
            size[i]=1;
        }
    }
    int root(int x){
        if(par[x]==x)return x;
        return root(par[x]);
    }
    void unite(int x, int y){
        int rx=root(x);
        int ry=root(y);
        if(rx==ry)return;
        if(size[rx]<size[ry]){
            par[rx]=ry;
            size[ry]+=size[rx];
        }else{
            par[ry]=rx;
            size[rx]+=size[ry];
        }
    }
    bool same(int x, int y){
        return root(x)==root(y);
    }
    int getSize(int x){
        return size[root(x)];
    }
};
int main(){
    int n=in(),m=in();
    UnionFind tree(n);
    rep(i,m){
        int x=in()-1,y=in()-1,z=in();
        tree.unite(x,y);
    }
    vector<bool> bl(n,false);
    rep(i,n){
        int r=tree.root(i);
        bl[r]=true;
    }
    int cnt=0;
    rep(i,n){
        if(bl[i])cnt++;
    }
    cout<<cnt<<endl;
}