#include<cstdio>

 #include<cstring>

 #include<vector>

 #include<stack>

 #include<algorithm>

 #define rep(i,a,b) for(int i=a;i<=b;i++)

 #define clr(a,m) memset(a,m,sizeof(a))

 using namespace std;

 const int MAXN=;

 const int MAXM=;

 struct Edge{

     int v,next,vis;

     Edge(){}

     Edge(int _v,int _next):v(_v),next(_next),vis(){}

 }edge[MAXM<<];

 stack<int>stk;

 int head[MAXN],tol;

 int degree[MAXN];

 void init()

 {

     tol=;

     clr(head,-);

 }

 void add(int u,int v)

 {

     edge[tol]=Edge(v,head[u]);

     head[u]=tol++;

     edge[tol]=Edge(u,head[v]);

     head[v]=tol++;

 }

 void FindEuler(int u)

 {

     for(int i=head[u];i!=-;i=edge[i].next)

     {

         int v=edge[i].v;

         if(!edge[i].vis){

             edge[i].vis=edge[i^].vis=;

             FindEuler(v);

             stk.push(v);

         }

     }

 }

 void EulerCircuit(int n)

 {

     while(!stk.empty())

         stk.pop();

     FindEuler();

 }

 int main()

 {

     int n,m,x,y;

     scanf("%d%d",&n,&m);

     init();

     clr(degree,);

     rep(i,,m-){

         scanf("%d%d",&x,&y);

         x--;y--;

         add(x,y);

         add(x,y);

         degree[x]+=;

         degree[y]+=;

     }

     EulerCircuit(n);

     stk.push();

     while(!stk.empty())

     {

         x=stk.top();stk.pop();

         printf("%d\n",x+);

     }

     return ;

 }