Facebook приятели

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <map>


using namespace std;

unordered_map<int, vector<int>> graph;

map<int, int> components;

void dfs(int start, vector<bool>& visited, int component){
    visited[start] = true;
    components[component]++;
    for(int neigh : graph[start]){
        if(!visited[neigh])
            dfs(neigh, visited, component);
    }
}

int main() {
    int n, e, k, a, b;
    cin >> n >> e >> k;
    for(int i = 0; i < e; i++){
        cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    vector<bool> visited(n, false);
    for(int i = 0; i < n; i++){
        if(!visited[i])
            dfs(i, visited, i);
    }
    int counter = 0;
    for(auto component : components){
        if(component.second % k == 0)
            counter++;
    }

    cout << counter;

    return 0;
}