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

#define MAX_NODES 100

typedef struct _adjlist {
     int node;
     struct _adjlist *link;
} adjlist;

adjlist graph[MAX_NODES];

int visited[MAX_NODES];    // 0:unvisited    1:visited

void insert(int v1, int v2);

void dfs(int v);



void insert(int v1, int v2)
{
    adjlist* newNode = malloc(sizeof(struct _adjlist));
    adjlist* tempNode = malloc(sizeof(struct _adjlist));

    newNode->node = v2;
    newNode->link = NULL;

    if(graph[v1].link == NULL) graph[v1].link = newNode;
    else {
        tempNode = graph[v1].link;
        while(tempNode->link != NULL) tempNode = tempNode->link;
        tempNode->link = newNode;
    }
}

void dfs(int v)
{
    /*
     Fill in your code here...
     visit v and traverse all its edges recursively.
     */
    adjlist *w;
    visited[v]= 1; printf("%d ",v);
    for (w = graph[v].link; w != NULL; w = w->link){
        if(visited[w->node] == 0){
            dfs(w->node);
        }
    }
}

int main()
{
    int m,a,b;

    // initialize
    for(int i=0;i<MAX_NODES;i++)
    {
                graph[i].link=NULL;
                visited[i]=0;  // unvisited
    }


    printf("Input the number of edges:\n");
    scanf("%d",&m);
    printf("Input these edges:\n");
    for(int i=0; i<m; i++)
    {
        scanf("%d %d", &a, &b);
        insert(a,b);
          insert(b,a);
    }
    //dfs(0);
    return 0;
}