#include <cstdio>
#include <vector>
#include <cstring>
#include <algorithm>
#define VMax 10000
#define NMax 1000
using namespace std;

vector<int> a[NMax+1];
int c[NMax+1][NMax+1];
int f[NMax+1][NMax+1];
int COADA[NMax+1];
int is[2][NMax+1];
int res[VMax+1];
int viz[NMax+1];
int st[VMax+1];
int dr[VMax+1];
int t[NMax+1];
int N,M;

int BFS()
{
    int i,x,y,inc,sf;

    memset(t, 0, sizeof(t));
    inc = sf = 0;
    COADA[0] = 1;
    while(inc <= sf)
    {
        x = COADA[inc++];
        for(i = 0; i < a[x].size(); ++i)
        {
            y = a[x][i];
            if(!t[y] && f[x][y] < c[x][y])
            {
                COADA[++sf] = y;
                t[y] = x;
            }
        }
    }

    return t[N];
}

void Path(int S, int l)
{
    int i,x,y,inc,sf,sgn=1;

    memset(viz, 0, sizeof(viz));
    if(l) sgn = -1;
    is[l][S] = 1;
    inc = sf = 0;
    COADA[0] = S;
    while(inc <= sf)
    {
        x = COADA[inc++];
        for(i = 0; i < a[x].size(); ++i)
        {
            y = a[x][i];
            if(!viz[y] && sgn * f[x][y] >= 0 && abs(f[x][y]) < c[x][y])
            {
                is[l][y] = viz[y] = 1;
                COADA[++sf] = y;
            }
        }
    }
}

int main(){
    FILE* fin = fopen("critice.in","r");
    FILE* fout = fopen("critice.out","w");

    int i,j,x,y,z,r,cnt=0;

    fscanf(fin,"%d %d",&N,&M);
    for(i = 1; i <= M; ++i)
    {
        fscanf(fin,"%d %d %d",&x,&y,&z);
        st[i] = x; dr[i] = y;
        c[x][y] = c[y][x] = z;
        a[x].push_back(y);
        a[y].push_back(x);
    }

    while(BFS())
        for(i = 0; i < a[N].size(); ++i)
        {
            x = a[N][i];
            if(!t[x] || c[x][N] == f[x][N]) continue;

            r = c[x][N] - f[x][N];
            for(j = x; j > 1; j = t[j]) r = min(r, c[ t[j] ][j] - f[ t[j] ][j]);
            if(!r) continue;

            f[x][N] += r;
            f[N][x] -= r;
            for(j = x; j > 1; j = t[j])
            {
                f[ t[j] ][j] += r;
                f[j][ t[j] ] -= r;
            }
        }

    Path(1,0);
    Path(N,1);
    for(i = 1; i <= M; ++i)
    {
        x = st[i];
        y = dr[i];
        if(f[x][y] < 0) swap(x,y);
        if(f[x][y] == c[x][y])
            if(is[0][x] && is[1][y]) ++cnt, res[i] = 1;
    }

    fprintf(fout,"%d\n",cnt);
    for(i = 1; i <= M; ++i)
        if(res[i]) fprintf(fout,"%d\n",i);


    return 0;
}