#include <stdio.h>
#include <stdlib.h>

typedef struct vertex {
	int name;
	struct vertex** neighbors;
	int numNeighbors;
	//	int* weights;
} vertex;

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

void dfs_pointers(graphVertex graph, int currentNode, int* visited)
{
	if (!visited[currentNode]) {
		//printf("%d ", currentNode);
		visited[currentNode] = 1;
		for (int i = 0; i < graph.nodes[currentNode].numNeighbors; i++)
			if (!visited[graph.nodes[currentNode].neighbors[i]->name])
				dfs_pointers(graph, graph.nodes[currentNode].neighbors[i]->name, visited);
	}
}

graphVertex readGraphVertex(const char* fileName)
{
	graphVertex graph;
	graph.numEdges = 0;
	graph.numNodes = 0;
	FILE* f = fopen(fileName, "r");
	if (f == NULL)
		return graph;

	fscanf(f, "%i%i", &(graph.numNodes), &(graph.numEdges));
	graph.nodes = (vertex*)malloc(sizeof(vertex) * (graph.numNodes + 1));
	if (graph.nodes == NULL)
		return graph;
	for (int i = 0; i <= graph.numNodes; i++) {
		graph.nodes[i].name = i;
		graph.nodes[i].numNeighbors = 0;
		graph.nodes[i].neighbors = NULL;
	}
	for (int i = 0; i < graph.numEdges; i++) {
		int x, y;
		fscanf(f, "%i%i", &x, &y);
		graph.nodes[x].numNeighbors++;
		graph.nodes[x].neighbors = (vertex**)realloc(graph.nodes[x].neighbors, graph.nodes[x].numNeighbors * sizeof(vertex*));
		graph.nodes[x].neighbors[graph.nodes[x].numNeighbors - 1] = &(graph.nodes[y]);
		graph.nodes[y].numNeighbors++;
		graph.nodes[y].neighbors = (vertex**)realloc(graph.nodes[y].neighbors, graph.nodes[y].numNeighbors * sizeof(vertex*));
		graph.nodes[y].neighbors[graph.nodes[y].numNeighbors - 1] = &(graph.nodes[x]);
	}
	fclose(f);
	return graph;
}

int main()
{
	graphVertex graphV = readGraphVertex("dfs.in");
	/*for (int i = 1; i <= graphV.numNodes; i++) {
		printf("%d ", graphV.nodes[i].numNeighbors);
	}*/
	int* visited = (int*)malloc(sizeof(int) * (graphV.numNodes + 1));
	int graphs = 0;
	//memset(visited, 0, graphV.numNodes);
	for (int i = 1; i <= graphV.numNodes; i++) visited[i] = 0;
	for (int i = 1; i <= graphV.numNodes; i++)
		if (!visited[i]) {
			graphs++;
			dfs_pointers(graphV, i, visited);
		}
	FILE* g = fopen("dfs.out", "w");
	fprintf(g, "%d", graphs);
	fclose(g);
	return 0;
}

/*int visited[100001];
int n, e;
int main()
{
	FILE* f = fopen("dfs.in", "r");
	fscanf(f, "%d %d", &n, &e);
	int numberGraphs = 0, color = 0;
	int x, y;
	for (int i = 0; i < e; i++) {
		fscanf(f, "%d %d", &x, &y);
		if (!visited[x] && !visited[y]) {
			numberGraphs++;
			color++;
			visited[x] = color;
			visited[y] = color;
		} else if (!visited[x])
			visited[x] = visited[y];
		else if (!visited[y])
			visited[y] = visited[x];
		else {
			//to do
			if (visited[x] != visited[y]) {
				numberGraphs--;
				int aux = visited[x];
				for (int j = 1; j <= n; j++)
					if (visited[j] == aux)
						visited[j] = visited[y];
				//to do parcurg si schimb culoarea
			}
			//else aceeasi culoare deci nimic
		}
	}
	for (int i = 1; i <= n; i++)
		if (!visited[i]) numberGraphs++;
	FILE* g = fopen("dfs.out", "w");
	fprintf(g, "%d", numberGraphs);
	fclose(f);
	fclose(g);
}
*/
/*int n, e;
int visited[100001];
typedef struct edge {
	int leftnode;
	int rightnode;
} edge;

void dfs(int currentNode, int graphColor, edge* edges, int* visited)
{
	if (!visited[currentNode]) {
		visited[currentNode] = graphColor;
		for (int i = 0; i < e; i++) {
			if (edges[i].leftnode == currentNode)
				dfs(edges[i].rightnode, graphColor, edges, visited);
			if (edges[i].rightnode == currentNode)
				dfs(edges[i].leftnode, graphColor, edges, visited);
		}
	}
}

int main()
{
	FILE* f = fopen("dfs.in", "r");
	fscanf(f, "%d %d", &n, &e);
	int numberGraphs = 0;
	edge* edges = (edge*)malloc(e * sizeof(edge));
	for (int i = 0; i < e; i++)
		fscanf(f, "%d %d", &edges[i].leftnode, &edges[i].rightnode);
	for (int i = 1; i <= n; i++) {
		if (!visited[i]) {
			numberGraphs++;
			dfs(i, numberGraphs, edges, visited);
		}
	}
	FILE* g = fopen("dfs.out", "w");
	fprintf(g, "%d", numberGraphs);
	fclose(f);
	fclose(g);
	/*for (int i = 1; i <= n; i++)
		printf("%d ", visited[i]);
}
*/