4.dfs

 #include <bits/stdc++.h>

#include <ext/pb_ds/assoc_container.hpp>

#include <ext/pb_ds/tree_policy.hpp>

using namespace std;

using namespace __gnu_pbds;

template <class type1>

#define ll long long int

#define endl "\n"

#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>

using ordered_multiset = tree <type1, null_type, less_equal <type1>, rb_tree_tag, tree_order_statistics_node_update>;

 //ordered_multiset <ll> kek;(declaration for multiorder set)

// ordered_set o_set;(declaration)

//kek.order_of_key(i);(strictly less then i for multi order set)

//o_set.order_of_key(5) ;(strictly less then i for multi order set)

#define yes cout << "YES\n"

#define no cout << "NO\n"

#define mod 1000000007

ll POW(ll a,ll b)

{   ll ans=1;

   while(b>0)

   {   if(b%2)ans=(ans*a)%mod;

       b/=2;

       a=(a*a)%mod;

   }

   return ans;

}

const ll N=1000;

vector<ll>adj[N];

ll vis[N];

vector<ll>ans;

void dfs(ll node)

{

     ans.push_back(node);

     vis[node]=1;

     for(ll i=0;i<adj[node].size();i++)

     {

          ll child=adj[node][i];

         if(vis[child]==0)

         {

             dfs(child);

         }

     }

}

int main()

{

    ios_base::sync_with_stdio(0);

    cin.tie(0);

    cout.tie(0);

   

   ll n,m,i;

   cin>>n>>m;

   for(i=1;i<=m;i++)

   {

       ll u,v;

       cin>>u>>v;

        adj[u].push_back(v);

        adj[v].push_back(u);

   }

   for(i=1;i<=n;i++)

   {

      if(vis[i]==0)

      {

         dfs(i);

      }

   }

   for(i=0;i<ans.size();i++)

   {

     cout<<ans[i]<<" ";

   }

   cout<<endl;

    return 0;

}