#include<fstream>
#include<vector>
#include<bitset>
using namespace std;
int n, m, i, x, y, z, nr, p, minim, nod, vecin;
int c[1005][1005], f[1005][1005], s[1005], t[1005], sol[10005], f1[2][1005];
vector<int> v[1005];
pair<int, int> w[10005];
bitset<1005> viz;
ifstream fin("critice.in");
ofstream fout("critice.out");
int bfs(){
    int p, u, vecin, nod, i;
    int ok = 0;
    viz.reset();
    viz[1] = 1;
    p = u = 1;
    s[1] = 1;
    while(p <= u){
        nod = s[p];
        for(i = 0; i < v[nod].size(); i++){
            vecin = v[nod][i];
            if(viz[vecin] == 0 && f[nod][vecin] < c[nod][vecin]){
                u++;
                s[u] = vecin;
                viz[vecin] = 1;
                t[vecin] = nod;
                if(vecin == n){
                    ok = 1;
                }
            }
        }
        p++;
    }
    return ok;
}

void bfs1(int start, int nr){
    int p, u, vecin, nod, i;
    viz.reset();
    viz[start] = 1;
    p = u = 1;
    s[1] = start;
    f1[nr][start] = 1;
    while(p <= u){
        nod = s[p];
        for(i = 0; i < v[nod].size(); i++){
            vecin = v[nod][i];
            if(viz[vecin] == 0 && (f[nod][vecin] < c[nod][vecin] && f[vecin][nod] < c[nod][vecin])){
                u++;
                s[u] = vecin;
                viz[vecin] = 1;
                f1[nr][vecin] = 1;
                t[vecin] = nod;
            }
        }
        p++;
    }
}
int main(){
    fin>> n >> m;
    for(i = 1; i <= m; i++){
        fin>> x >> y >> z;
        c[x][y] = z;
        c[y][x] = z;
        v[x].push_back(y);
        v[y].push_back(x);
        w[i].first = x;
        w[i].second = y;
    }

    while(bfs()){
        for(i = 0; i < v[n].size(); i++){
            vecin = v[n][i];
            if(viz[vecin] == 1 && f[vecin][n] < c[vecin][n]){
                minim = c[vecin][n] - f[vecin][n];
                p = vecin;
                while(t[p] > 0){
                    minim = min(minim, c[ t[p] ][p] - f[ t[p] ][p]);
                    p = t[p];
                }
                f[vecin][n] += minim;
                f[n][vecin] -= minim;
                 p = vecin;
                while(t[p] > 0){
                    f[ t[p] ][p] += minim;
                    f[p][ t[p] ] -= minim;
                    p = t[p];
                }
            }
        }
    }
    bfs1(1, 0);
    bfs1(n, 1);
    for(i = 1; i <= m; i++){
        x = w[i].first;
        y = w[i].second;
        if(f[x][y] == c[x][y] && f1[0][x] == 1 && f1[1][y] == 1){
            nr++;
            sol[nr] = i;
        }
        else{
             if(f[y][x] == c[y][x] && f1[0][y] == 1 && f1[1][x] == 1){
                nr++;
                sol[nr] = i;
            }
        }
    }
    fout<< nr <<"\n";
    for(i = 1; i <= nr; i++){
        fout<< sol[i] <<"\n";
    }
    return 0;
}