#include <cstdio>
#include <string>
using namespace std;
FILE *fin=fopen("critice.in","r");
FILE *fout=fopen("critice.out","w");
#define nmax 1005
#define mmax 10002
#define inf 1<<18
struct muchie
 {
 int x,y;
 };
muchie M[mmax];
int C[nmax][nmax],Fx[nmax][nmax];
int sol[mmax],nr;
int pre[nmax];
int Q[nmax*5],k;
int f[nmax];
int s[nmax];
int n,m;
#define Q (Q-1)
bool viz[nmax];
struct graf
 {
 int x;
 graf *urm;
 };
graf *G[nmax];
inline int min(int x,int y)
 {
 if(x<y) return x;
 return y;
 }
void add(graf *&g,int x)
 {
 graf *p=new graf;
 p->x=x;
 p->urm=g;
 g=p;
 }
void read()
 {
 fscanf(fin,"%d %d",&n,&m);
 int i,x,y,c;
 for(i=1;i<=m;i++)
  {
  fscanf(fin,"%d %d %d",&x,&y,&c);
  M[i].x=x;
  M[i].y=y;
  C[x][y]=c;
  C[y][x]=c;
  add(G[x],y);
  add(G[y],x);
  }
 }
bool bfs()
 {
 k=0;
 Q[++k]=1;
 int i,x;
 bool ok=false;
 for(i=1;i<=n;i++) {pre[i]=-1;viz[i]=false;}
 viz[1]=true;
 for(i=1;i<=k&&!ok;i++)
  {
  x=Q[i];
  for(graf *g=G[x];g!=NULL&&!ok;g=g->urm)
   {
   if(!viz[g->x]&&C[x][g->x]-Fx[x][g->x]>0)
    {
    f[g->x]=min(f[x],C[x][g->x]-Fx[x][g->x]);
    pre[g->x]=x;
	viz[g->x]=true;
	Q[++k]=g->x;
	if(g->x==n)
	 ok=true;
    }
   }
  }
 return viz[n];
 }
void bfs(int nod,int z)
 {
 k=0;
 memset(viz,false,sizeof(viz));
 Q[++k]=nod;
 viz[nod]=true;
 int i,x;
 for(i=1;i<=k;i++)
  {
  x=Q[i];
  s[x]=z;
  for(graf *g=G[x];g!=NULL;g=g->urm)
   {
   if(!viz[g->x]&&((z==1)?(C[x][g->x]-Fx[x][g->x]>0):(C[g->x][x]-Fx[g->x][x]>0)))
    {
    viz[g->x]=true;
    Q[++k]=g->x;
    }
   }
  }
 }
void solve()
 {
 bfs(1,1);
 bfs(n,2);
 int i,x,y;
 for(i=1;i<=m;i++)
  {
  x=M[i].x;
  y=M[i].y;
  if( (!(C[x][y]-Fx[x][y]) && (C[y][x]-Fx[y][x]) || !(C[y][x]-Fx[y][x]) && (C[x][y]-Fx[x][y])) && (s[x]+s[y]==3))
   sol[++nr]=i;
  }
 fprintf(fout,"%d\n",nr);
 for(i=1;i<=nr;i++)
  fprintf(fout,"%d\n",sol[i]);
 }
int main()
 {
 int i;
 read();
 f[1]=inf;
 while(bfs())
  {
  for(i=n;pre[i]!=-1;i=pre[i])
   {
   Fx[pre[i]][i]+=f[n];
   Fx[i][pre[i]]-=f[n];
   }
  f[1]=inf;
  }
 solve();
 return 0;
 }