//By SiriusRen
#include <bits/stdc++.h>
using namespace std;
const int N=20050;
int n,m,xx,yy,v[N],next[N],first[N],tot,num,T,stk[N],a[N],odd,R[N],remm,lastT,rev[N],fa[N],vis[N],size[N],son[N],dfn[N],cnt,top[N],deep[N],ans,ra[N];
struct Node{int x,y,wei;}rec[N];
void add(int x,int y){v[tot]=y,next[tot]=first[x],first[x]=tot++;}
void dfs1(int x){size[x]=1,vis[x]=1,rev[++T]=x,stk[T]=x;for(int i=first[x];~i;i=next[i])if(v[i]!=fa[x]){if(vis[v[i]]){rec[++num].x=x,rec[num].y=v[i],rec[num].wei=i/2+1;continue;}R[v[i]]=i/2+1,deep[v[i]]=deep[x]+1,fa[v[i]]=x;dfs1(v[i]),size[x]+=size[v[i]];if(size[v[i]]>size[son[x]])son[x]=v[i];}
}
void dfs2(int x,int tp){vis[x]=1,dfn[x]=++cnt;top[x]=tp;if(son[x])dfs2(son[x],tp);for(int i=first[x];~i;i=next[i])if(v[i]!=fa[x]&&v[i]!=son[x]&&!vis[v[i]])dfs2(v[i],v[i]);
}
int lca(int x,int y){int fx=top[x],fy=top[y];while(fx!=fy){if(deep[fx]<deep[fy])swap(fx,fy),swap(x,y);x=fa[fx],fx=top[x];}if(deep[x]<deep[y])return x;return y;
}
int main(){memset(first,-1,sizeof(first));scanf("%d%d",&n,&m);for(int i=1;i<=m;i++)scanf("%d%d",&xx,&yy),add(xx,yy),add(yy,xx);for(int i=1;i<=n;i++)if(!vis[i]){dfs1(i);for(int j=lastT;j<=T;j++)vis[rev[j]]=0;dfs2(i,i);lastT=T;}for(int i=1;i<=num;i++){if((deep[rec[i].x]%2)==(deep[rec[i].y]%2))a[rec[i].x]++,a[rec[i].y]++,a[lca(rec[i].x,rec[i].y)]-=2,odd++,remm=rec[i].wei;else a[rec[i].x]--,a[rec[i].y]--,a[lca(rec[i].x,rec[i].y)]+=2;}if(!odd){printf("%d\n",m);for(int i=1;i<=m;i++)printf("%d ",i);return 0;}for(int i=n;i;i--)a[fa[stk[i]]]+=a[stk[i]];for(int i=1;i<=n;i++)if(a[i]==odd)ra[++ans]=R[i];if(odd==2)ra[++ans]=remm;printf("%d\n",ans),sort(ra+1,ra+1+ans);for(int i=1;i<=ans;i++)printf("%d ",ra[i]);
}