#include <bits/stdc++.h>
#define scan(x) do{while((x=getchar())<'0'); for(x-='0'; '0'<=(_=getchar()); x=(x<<3)+(x<<1)+_-'0');}while(0)
char _;
using namespace std;
const int maxn = 1e5+10;
typedef pair<int, int> pii;
bool markEdge[maxn], mark[maxn];
vector<pii> grafo[maxn];
stack<int> stk;
void dfs(int u)
{
if (mark[u])
{
while (true)
{
int v = stk.top();
stk.pop();
mark[v] = 0;
if (v == u)
{
printf("%d\n", v);
break;
}
printf("%d ", v);
}
}
for (auto v: grafo[u])
{
if (!markEdge[v.second])
{
mark[u] = 1;
stk.push(u);
markEdge[v.second] = 1;
dfs(v.first);
}
}
}
int main(void)
{
int n, m;
scan(n); scan(m);
for (int i = 1; i <= m; i++)
{
int u, v;
scan(u); scan(v);
grafo[u].push_back({v, i});
grafo[v].push_back({u, i});
}
dfs(1);
}
