#include <iostream>

 #include <stdio.h>

 #include <string.h>

 #include <cmath>

 #include <algorithm>

 #include <queue>

 #include <vector>

 using namespace std;

 #define MAXN 310

 #define CLR(a,b) memset(a,b,sizeof(a))

 deque<int> Q;

 //g[i][j]存放关系图：i,j是否有边,match[i]存放i所匹配的点

 bool g[MAXN][MAXN],inque[MAXN],inblossom[MAXN];

 int match[MAXN],pre[MAXN],base[MAXN];

 //找公共祖先

 int findancestor(int u,int v)

 {

     bool inpath[MAXN]={false};

     while()

     {

         u=base[u];

         inpath[u]=true;

         if(match[u]==-)break;

         u=pre[match[u]];

     }

     while()

     {

         v=base[v];

         if(inpath[v])return v;

         v=pre[match[v]];

     }

 }

 //压缩花

 void reset(int u,int anc)

 {

     while(u!=anc)

     {

         int v=match[u];

         inblossom[base[u]]=;

         inblossom[base[v]]=;

         v=pre[v];

         if(base[v]!=anc)pre[v]=match[u];

         u=v;

     }

 }

 void contract(int u,int v,int n)

 {

     int anc=findancestor(u,v);

     CLR(inblossom,);

     reset(u,anc);reset(v,anc);

     if(base[u]!=anc)pre[u]=v;

     if(base[v]!=anc)pre[v]=u;

     for(int i=;i<=n;i++)

         if(inblossom[base[i]])

         {

             base[i]=anc;

             if(!inque[i])

             {

                 Q.push_back(i);

                 inque[i]=;

             }

         }

 }

 bool dfs(int S,int n)

 {

     for(int i=;i<=n;i++)pre[i]=-,inque[i]=,base[i]=i;

     Q.clear();Q.push_back(S);inque[S]=;

     while(!Q.empty())

     {

         int u=Q.front();Q.pop_front();

         for(int v=;v<=n;v++)

         {

             if(g[u][v]&&base[v]!=base[u]&&match[u]!=v)

             {

                 if(v==S||(match[v]!=-&&pre[match[v]]!=-))contract(u,v,n);

                 else if(pre[v]==-)

                 {

                     pre[v]=u;

                     if(match[v]!=-)Q.push_back(match[v]),inque[match[v]]=;

                     else

                     {

                         u=v;

                         while(u!=-)

                         {

                             v=pre[u];

                             int w=match[v];

                             match[u]=v;

                             match[v]=u;

                             u=w;

                         }

                         return true;

                     }

                 }

             }

         }

     }

     return false;

 }

 int solve(int n)

 {

     CLR(match,-);

     int ans=;

     for(int i=;i<=n;i++)

         if(match[i]==-&&dfs(i,n))

             ans++;

     return ans;

 }

 /*--  以上为带花树求一般图最大匹配的模板   --*/

 bool vis[];

 int a[],b[];

 int main() {

     int n , m;

     while(scanf("%d%d",&n,&m) != EOF) {

         CLR(g,false);CLR(vis,false);

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

            scanf("%d%d",&a[i],&b[i]);

            g[a[i]][b[i]] = g[b[i]][a[i]] = true;

        }

        int ans = solve(n);

        vector<int> vec;

        for(int i = ; i <= m; i++) {   //枚举不进行匹配边

            int x = a[i]  , y = b[i];

            CLR(g,false);     //清空匹配关系，接下来进行重置

            for(int j = ; j <= m; j++) if(i!=j){

                int tmp1 = a[j] , tmp2 = b[j];

                if(tmp1==x||tmp1==y||tmp2==x||tmp2==y)continue;   //为什么是将所有包含这两点之间匹配关系的全部(即删除点)清除 ???

                g[tmp1][tmp2] = g[tmp2][tmp1] = true;

            }

            int tmp = solve(n);

            if(tmp != ans - ) {   //如果删除这条边后，最大匹配数不是原始值-1，说明这条边不在最大匹配中

                    vec.push_back(i);

            }

        }

        printf("%d\n",vec.size());

        if(vec.size()>) {

            printf("%d",vec[]);

            for(int i = ; i < vec.size(); i++) {

                printf(" %d",vec[i]);

            }

        }

        puts("");

     }

     return ;

 }