counts number of connected components (using dfs)

#include <bits/stdc++.h>
using namespace std;
#define ll long long
bool visited[10000]={0};
int counter=0;
vector <int> adj[10000];
void dfs(int k){
    visited[k]=true;
    for (auto u:adj[k]){
        if (!visited[u]){
            dfs(u);
        }
    }
}
void connected(int x){
    if (!visited[x]){
        counter++;
        dfs(x);
    }
}
int main()
{
    int n,m;
    cin>>n>>m;
    for (int i=0; i<m; i++){
        int x,y;
        cin>>x>>y;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
    for (int i=1; i<=n; i++){
        connected(i);
    }
    cout<<counter<<"\n";
}