DFS

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
#include <vector>

using namespace std;

#define si(a) scanf("%d",&a)
#define f first
#define s second
#define mp(a,b) make_pair(a,b)
#define MAX 1005

int vis[MAX];
vector<int> graph[MAX];

void dfs(int now)
{
    if(vis[now])
        return ;
    //cout<<now+1<<endl;
    vis[now]=1;
    for(int i=0;i<graph[now].size();i++)
        dfs(graph[now][i]);
    return ;
}

int main()
{
    //freopen("input","r",stdin);
    int n,m,i;
    si(n);si(m);
    for(i=0;i<m;i++){
        int u,v;
        si(u);si(v);
        u--;v--;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }
    dfs(0);
    return 0;
}