#include<iostream>

#include<cstdio>

#include<cstring>

#include<algorithm>

using namespace std;

int const maxn=2e4+;

int n,m,fa[maxn],sf[maxn],sg[maxn],g[maxn],f[maxn],ans[maxn],ns;

int col[maxn],hd[maxn],ct,cnt,qhd[maxn],numj;

bool vis[maxn];

struct N{

    int to,nxt,edge;

    N(int t=,int n=,int e=):to(t),nxt(n),edge(e) {}

}ed[maxn<<],q[maxn];

struct T{

    int ff,gg;

    T(int f=,int g=):ff(f),gg(g) {}

};

inline int rd()

{

    int ret=,f=;char ch=getchar();

    while(ch<''||ch>''){if(ch=='-')f=-; ch=getchar();}

    while(ch>=''&&ch<='')ret=ret*+ch-'',ch=getchar();

    return ret*f;

}

inline int find(int x){return fa[x]==x?x:fa[x]=find(fa[x]);}

inline void add(int x,int y,int e){ed[++ct]=N(y,hd[x],e); hd[x]=ct;}

inline void ad(int x,int y,int e){q[++cnt]=N(y,qhd[x],e); qhd[x]=cnt;}

inline void dfs2(int x,int pre)

{

    vis[x]=; col[x]=!col[pre];

    for(register int i=qhd[x];i;i=q[i].nxt)

    {

        int u=q[i].to;

        if(!vis[u])continue;

        int lca=find(u);

        if(col[u]==col[x])

        {

//            f[u]++,f[i]++,f[pr[lca]]-=2,numj++;

            f[u]++,f[x]++,f[lca]-=,numj++;

            sf[q[i].edge]=;

        }

        else

        {

//            g[u]++,g[i]++,g[pr[lca]]-=2,numo++;

            g[u]++,g[x]++,g[lca]-=;

        }

    }

    for(register int i=hd[x],u;i;i=ed[i].nxt)

        if((u=ed[i].to)!=pre)dfs2(u,x);

    fa[x]=pre;

}

inline T dfs3(int x,int pre)

{

    int smf=f[x],smg=g[x]; vis[x]=;//smf,smg!=0!!!

    for(register int i=hd[x],u;i;i=ed[i].nxt)

    {

        if((u=ed[i].to)==pre)continue;

        T k=dfs3(u,x);int e=ed[i].edge;

        sf[e]=k.ff; sg[e]=k.gg;

        smf+=k.ff; smg+=k.gg;

    }

    return T(smf,smg);

}

int main()

{

    n=rd(); m=rd();

    for(register int i=;i<=n;i++)fa[i]=i;

    for(register int i=,u,v;i<=m;i++)

    {

        u=rd(); v=rd();

        if(find(u)!=find(v))

        {

            fa[find(u)]=find(v);

            add(u,v,i); add(v,u,i);

        }

        else ad(u,v,i),ad(v,u,i);

    }

    for(register int i=;i<=n;i++)fa[i]=i;

    for(int i=;i<=n;i++)if(!vis[i])dfs2(i,);//不仅dfs(1,0)

    memset(vis,,sizeof vis);

    if(!numj)

    {

        printf("%d\n",m);

        for(int i=;i<=m;i++)printf("%d ",i);

        return ;

    }

    for(int i=;i<=n;i++)if(!vis[i])dfs3(i,);

    memset(vis,,sizeof vis);

    for(register int i=;i<=m;i++)

        if(sf[i]==numj&&!sg[i])ans[++ns]=i;

    printf("%d\n",ns);

    sort(ans+,ans+ns+);

    for(register int i=;i<=ns;i++)printf("%d ",ans[i]);

    return ;

}