#include<fstream>
#include<bitset>
#include<vector>
#define Nmax 100009
#define Mmax 500009
#define x first
#define y second
using namespace std;
ifstream f("ciclueuler.in");
ofstream g("ciclueuler.out");
typedef pair<int,int> PP;
int N,M,x,y;
vector <int> G[Nmax],Cycle;
PP E[Mmax];
bitset <Mmax> viz;

inline int IsEulerian()
{
    for(int i=1;i<=n;++i)
        if(G[i].size() &1) return 0;
    return 1;
}

inline void DFS(int node)
{
    vector <int> :: iterator it;
    for(it=G[node].begin();it!=G[node].end();++it)
        if(!viz[*it]) , DFS(E[*it].x+E[*it].y-node);
    Cycle.push_back(node);
}

int main()
{
    f>>N>>M;
    for(int i=1;i<=M;++i){
        f>>x>>y;
        G[x].push_back(i);
        G[y].push_back(i);
        E[i]=PP(x,y);
    }
    if(IsEulerian()){
        DFS(1);
        vector <int> :: iterator it;
        for(it=G[node].begin();it!=G[node].end();++it)
        g<<*it<<' ';
        g<<'\n';
    }
    else g<<-1<<'\n';
    f.close();g.close();
    return 0;
}