#include <bits/stdc++.h>
#include <cstdio>
#pragma GCC optimize("O3")
#define fr(i, n, m) for(int i = (n); i < (m); i ++)
#define pb push_back
#define st first
#define nd second
#define pq priority_queue
#define all(x) begin(x), end(x)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
const ll inf = 1e18;
const ll mod = 1000000007;
const ld eps = 1e-13;
const ld pi = 3.14159265359;
mt19937 _rand(time(NULL));
clock_t timer = clock();
const int mxn = 5*1e5+5;
inline int readint(){
int ret=0;
for(char c;;){
c=getchar_unlocked();
if('0'<=c and c<='9')
ret=ret*10+(c&15);
else
return ret;
}
}
vector<char> digits;
inline void printint(int x){
do{
digits.push_back(x%10|48);
x/=10;
}while(x);
while(not digits.empty())
putchar(digits.back()), digits.pop_back();
}
int n, m;
vector<int> g[mxn];
int deg[mxn];
bool used[mxn];
int l[mxn], r[mxn];
vector<int> cycle;
void euler(int u){
while(deg[u] > 0){
int e = g[u][deg[u]-1];
int v = l[e];
if(v == u) v = r[e];
--deg[u];
if(used[e]) continue;
used[e] = true;
euler(v);
}
cycle.pb(u);
}
bool vis[mxn];
int main(){
digits.reserve(10);
n=readint(), m=readint();
fr(i, 0, m){
l[i] = readint(), r[i] = readint();
--l[i], --r[i];
++deg[l[i]];
++deg[r[i]];
g[l[i]].pb(i);
g[r[i]].pb(i);
}
euler(0);
stack<int> S;
for(auto u : cycle){
if(vis[u]){
while(1){
int x = S.top();
printint(x+1);
putchar(' ');
S.pop();
vis[x] = false;
if(x == u){
putchar('\n');
break;
}
}
}
vis[u] = true;
S.push(u);
}
}
