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| #include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define maxn 100005
#define put() putchar('\n')
#define Tp template<typename Ty>
#define Ts template<typename Ty,typename... Ar>
using namespace std;
inline void read(int &x){
int f=1;x=0;char c=getchar();
while (c<'0'||c>'9') {if (c=='-') f=-1;c=getchar();}
while (c>='0'&&c<='9') {x=x*10+c-'0';c=getchar();}
x*=f;
}
namespace Debug{
Tp void _debug(char* f,Ty t){cerr<<f<<'='<<t<<endl;}
Ts void _debug(char* f,Ty x,Ar... y){while(*f!=',') cerr<<*f++;cerr<<'='<<x<<",";_debug(f+1,y...);}
Tp ostream& operator<<(ostream& os,vector<Ty>& V){os<<"[";for(auto& vv:V) os<<vv<<",";os<<"]";return os;}
#define gdb(...) _debug((char*)#__VA_ARGS__,__VA_ARGS__)
}using namespace Debug;
int n,m;
int h[maxn],head=1;
struct yyy{
int to,z,flag;
inline void add(int x,int y) {
to=y;z=h[x];h[x]=head;
}
}a[maxn*2];
int cnt;
int dfn[maxn],low[maxn],times,stac[maxn],tot,stace[maxn];
int Ans[maxn];
inline void tarjan(int x,int pre) {
int i;
dfn[x]=low[x]=++times;stac[++tot]=x;
for (i=h[x];i;i=a[i].z) {
int m=cnt;
if (!a[i].flag) stace[++cnt]=i/2,a[i].flag=a[i^1].flag=1;
if (!dfn[a[i].to]) {
tarjan(a[i].to,x);
low[x]=min(low[x],low[a[i].to]);
if (dfn[x]<=low[a[i].to]) {
int num=1;
while (stac[tot+1]!=a[i].to) tot--,num++;
int flag=(num==cnt-m);
while (cnt>m) Ans[stace[cnt]]=flag,cnt--;
}
}
else if (a[i].to^pre) low[x]=min(low[x],dfn[a[i].to]);
}
}
signed main(void){
int i,x,y;
read(n);read(m);
for (i=1;i<=m;i++) {
read(x);read(y);
a[++head].add(x,y);
a[++head].add(y,x);
}
for (i=1;i<=n;i++) if (!dfn[i]) tarjan(i,0);
int num=0;
for (i=1;i<=m;i++) num+=Ans[i];
for (printf("%d\n",num),i=1;i<=m;i++) if (Ans[i]) printf("%d ",i);
return 0;
}
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