#include<iostream>#include<cstdio>#include<string>#include<cstring>#include<algorithm>#include<stack>using namespace std;#define MIN(a,b) ((a<b)?(a):(b))#define MAX(a,b) ((a>b)?(a):(b))#define maxn 200010stack<int>sta;int in_sta[maxn],Low[maxn],head1[maxn],head2[maxn];int n,m,id,now,dfn[maxn],low[maxn],ans[maxn],t_ans;int te1,te2,vis[maxn];struct q{int x,y,pos,next;}e1[maxn],e2[maxn];void add1(int a,int b,int c){e1[te1].x=a;e1[te1].y=b;e1[te1].pos=c;e1[te1].next=head1[a];head1[a]=te1++;}void add2(int a,int b,int c){e2[te2].x=a;e2[te2].y=b;e2[te2].pos=c;e2[te2].next=head2[a];head2[a]=te2++;}void init(){id=now=0;t_ans=0;te1=1,te2=1;while(!sta.empty())sta.pop();memset(vis,0,sizeof(vis));memset(dfn,0,sizeof(dfn));memset(low,0,sizeof(low));memset(head1,0,sizeof(head1));memset(head2,0,sizeof(head2));memset(in_sta,0,sizeof(in_sta));memset(Low,0,sizeof(Low));}void tarjan(int u,int pre){Low[u]=dfn[u]=++now;int i;in_sta[u]=1;sta.push(u);int f1=1;for(i=head1[u];i;i=e1[i].next){int v=e1[i].y;if(f1&&v==pre){f1=0;continue;}if(!dfn[v]){tarjan(v,u);Low[u]=MIN(Low[u],Low[v]);}elseif(in_sta[v])Low[u]=MIN(Low[u],dfn[v]);}if(Low[u]==dfn[u]){id++;while(!sta.empty()){int v=sta.top();sta.pop();in_sta[v]=0;low[v]=id;if(v==u)break;}}}bool dfs(int u){vis[u]=1;if(u==low[n-1])return true;int i;for(i=head2[u];i;i=e2[i].next){int v=e2[i].y;if(!vis[v]&&dfs(v)){ans[t_ans++]=e2[i].pos;return true;}}return false;}int main(){int i;while(scanf("%d%d",&n,&m)!=EOF){init();for(i=0;i<m;i++){int x,y;scanf("%d%d",&x,&y);if(x==y)continue;add1(x,y,i);add1(y,x,i);}for(i=0;i<n;i++)if(!dfn[i])tarjan(i,-1);if(low[0]==low[n-1]){printf("0nn");continue;}for(i=1;i<te1;i++)if(low[e1[i].x]!=low[e1[i].y])add2(low[e1[i].x],low[e1[i].y],e1[i].pos);if(dfs(low[0])){sort(ans,ans+t_ans);printf("%dn%d",t_ans,ans[0]);for(i=1;i<t_ans;i++)printf(" %d",ans[i]);printf("n");}}return 0;}
