#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#define size 100000
int visited[size] = { 0 };
typedef struct vertex
{
	int name;
	int numNeighbours;
	vertex** neighbours;
}vertex;

typedef struct GraphVertex
{
	int numNodes;
	int numEdges;
	vertex* nodes;
}GraphVertex;


GraphVertex ReadFile()
{
	FILE* fptr = fopen("dfs.in", "r");
	GraphVertex graph;
	fscanf(fptr, "%d %d", &graph.numNodes, &graph.numEdges);
	graph.nodes = (vertex*)malloc(graph.numNodes * sizeof(vertex));

	for (int i = 0; i < graph.numNodes; i++)
	{	
		graph.nodes[i].numNeighbours = 0;
		graph.nodes[i].neighbours = NULL;
		graph.nodes[i].name = i + 1;
	}
	int aux = graph.numEdges;
	int left, right;
	while (aux)
	{
		fscanf(fptr, "%d %d", &left, &right);
		graph.nodes[left - 1].neighbours = (vertex**)realloc(graph.nodes[left - 1].neighbours, (graph.nodes[left - 1].numNeighbours + 1) * sizeof(vertex*));
		graph.nodes[left - 1].neighbours[graph.nodes[left - 1].numNeighbours] = graph.nodes+(right-1);
		graph.nodes[right - 1].neighbours = (vertex**)realloc(graph.nodes[right - 1].neighbours, (graph.nodes[right - 1].numNeighbours + 1) * sizeof(vertex*));
		graph.nodes[right - 1].neighbours[graph.nodes[right - 1].numNeighbours] = graph.nodes + (left - 1);
		graph.nodes[left - 1].numNeighbours++;
		graph.nodes[right - 1].numNeighbours++;
		aux--;
	}

	fclose(fptr);
	return graph;
}
void DFS(GraphVertex graph, int current)
{
	visited[current] = 1;
	for (int i = 0; i < graph.nodes[current].numNeighbours; i++)
		if (!visited[graph.nodes[current].neighbours[i]->name-1])
			DFS(graph, graph.nodes[current].neighbours[i]->name-1);
}
int main()
{
	GraphVertex graph = ReadFile();
	int componente=0;
	for (int i = 0; i < graph.numNodes; i++)
	{
		if (!visited[i])
		{
			DFS(graph, i);
			componente++;
		}
	}
	FILE* out =fopen ("dfs.out", "w");
	fprintf(out, "%d", componente);
	fclose(out);

	return 0;
}