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

#define MAX_NODES 101000

typedef struct Node {
    void *data;
    struct 
    Node *next;
} Node;

typedef struct {
    Node *head;
    Node *tail;
    int size;
} LinkedList;

typedef struct {
    LinkedList **neighbors;       
    int nodes;                   
} ListGraph;


void init_list(LinkedList *list) {
    list->head = NULL;
    list->tail = NULL;
    list->size = 0;
}

void add_nth_node(LinkedList *list, int n, void *new_data) {
    Node *prev, *curr;
    Node *new_node;

    if (list == NULL) {
        return;
    }

    if (n > list->size) {
        n = list->size;
    } else if (n < 0) {
        return;
    }

    curr = list->head;
    prev = NULL;
    while (n > 0) {
        prev = curr;
        curr = curr->next;
        --n;
    }

    new_node = malloc(sizeof(Node));
    if (new_node == NULL) {
        perror("Not enough memory to add element!");
        exit(-1);
    }
    
    new_node->data = new_data;
    new_node->next = curr;
    if (prev == NULL) {
        /* Adica n == 0. */
        list->head = new_node;
    } else {
        prev->next = new_node;
    }

    if (new_node->next == NULL) {
        list->tail = new_node;
    }

    list->size++;
}

Node* remove_nth_node(LinkedList *list, int n) {
    Node *prev, *curr;

    if (list == NULL) {
        return NULL;
    }

    if (list->head == NULL) { /* Lista este goala. */
        return NULL;
    }

    if (n > list->size - 1) {
        n = list->size - 1;
    } else if (n < 0) {
        return NULL;
    }

    curr = list->head;
    prev = NULL;
    while (n > 0) {
        prev = curr;
        curr = curr->next;
        --n;
    }

    if (prev == NULL) {
        /* Adica n == 0. */
        list->head = curr->next;
    } else {
        prev->next = curr->next;

        if (prev->next == NULL) {
            list->tail = prev;
        }
    }

    list->size--;
    return curr;
}

int get_size(LinkedList *list) {
    if (list == NULL) {
        return -1;
    }

    return list->size;
}

void free_list(LinkedList **pp_list) {
    struct Node *currNode;

    if (pp_list == NULL || *pp_list == NULL) {
        return;
    }

    while(get_size(*pp_list) > 0) {
        currNode = remove_nth_node(*pp_list, 0);
        free(currNode);
    }

    free(*pp_list);
    *pp_list = NULL;
}

void init_list_graph(ListGraph *graph, int nodes) {
     graph->nodes = nodes;
    graph->neighbors = malloc(nodes * sizeof(LinkedList));

    if (graph->neighbors == NULL) {
        perror("Not enough memory to initialize the adjacency list!");
        exit(-1);
    }

    for (int i = 0; i < nodes; ++i) {
        graph->neighbors[i] = malloc(sizeof(LinkedList));

        if (graph->neighbors[i] == NULL) {
            perror("Not enough memory to initialize the adjacency list!");
            exit(-1);
        }
        init_list(graph->neighbors[i]);
    }
}

void add_edge_list_graph(ListGraph *graph, int src, int *dest) {
    add_nth_node(graph->neighbors[src] , 0x7fffffff, dest);
    
}

int has_edge_list_graph(ListGraph *graph, int src, int dest) {
    Node *head = graph->neighbors[src]->head;
    int crt_node;

    while (head != NULL) {
        crt_node = *(int *)head->data;

        if (crt_node == dest) {
            return 1;
        }
        head = head->next;
    }

    return 0;
}

LinkedList* get_neighbours_list_graph(ListGraph *graph, int node) {
    return graph->neighbors[node];
}

void remove_edge_list_graph(ListGraph *graph, int src, int dest) {
    struct Node *curr;
    int poz;
    poz = 0;
    curr=(graph->neighbors[src])->head;
    
    while( curr!=NULL) {
        if(*((int *)curr->data) == dest) {
            remove_nth_node(graph->neighbors[src],poz);
        }
    poz++;
    curr = curr->next;
    }

}

void clear_list_graph(ListGraph *graph) {
    int i;
    for(i = 0; i < graph->nodes; i++) {
        free_list(&graph->neighbors[i]);
    }
    free(graph->neighbors);
    
}
void dfs_list_graph(ListGraph *lg, int node, int *visited, int *t_desc, int *t_fin, int *time) {
	struct Node *curr;
	int i;
	curr = lg->neighbors[node]->head; 

	visited[node] = 1;
	t_desc[node] = (*time)++;
	while(curr!=NULL) {
		i = *((int*)curr->data);

		if(visited[i] == 0) {
			dfs_list_graph(lg,i,visited,t_desc,t_fin,time);
		}
		curr = curr->next;
	}
	
	t_fin[node] = (*time)++;
}

int main(void) {
    int nodes, edges, node, i;
    int x[MAX_NODES], y[MAX_NODES];
    int visited[MAX_NODES];
    int parents[MAX_NODES], dist[MAX_NODES],t_desc[MAX_NODES],t_fin[MAX_NODES];
    int time;

    FILE *fin,*fout;
    fin = fopen("dfs.in","rt");

    if(fin==NULL) {
        printf("NU se poate deschide fisierul");
        return 0;
    }

    fout = fopen("dfs.out","wt");

    if(fout==NULL) {
        printf("NU se poate deschide fisierul");
        return 0;
    }

    ListGraph *lg = malloc(sizeof(ListGraph));

    fscanf(fin,"%d %d", &nodes, &edges);

    init_list_graph(lg, nodes);

    for (int i = 0; i < edges; ++i) {
        fscanf(fin,"%d %d", &x[i], &y[i]);
        x[i]=x[i]-1;
        y[i]=y[i]-1;
        add_edge_list_graph(lg, x[i], &y[i]);
        add_edge_list_graph(lg, y[i], &x[i]);
    }
    
    for(i = 0; i <= nodes; i++){
        dist[i] = 0;
        visited[i] = 0;
}
    time = 0;
    int nr;
    nr = 0;

    for(i = 0; i< nodes; i++) {
        if(visited[i] == 0) {
         dfs_list_graph(lg, i, visited, t_desc, t_fin, &time);
            nr++;
        }
    }

   fprintf(fout,"%d", nr);

    clear_list_graph(lg);
    free(lg);
    fclose(fin);
    fclose(fout);
    return 0;
}