#include <stdio.h>
#include <string.h>
#include <vector>

using namespace std;

#define MAX_N 1024

vector <int> vec[MAX_N];
int n, m, i, j, k, p, q, cpct, improve;
int c[MAX_N][MAX_N], ind[MAX_N][MAX_N];
int Q[MAX_N], flux[MAX_N], tata[MAX_N], d[MAX_N], sol[MAX_N * 10];

void cit() {
    freopen("critice.in", "r", stdin);
    freopen("critice.out", "w", stdout);

    scanf("%d %d", &n, &m);
    for (i = 1; i <= m; i++) {
	scanf("%d %d %d", &p, &q, &cpct);
	ind[p][q] = ind[q][p] = i;

	vec[p].push_back(q);
	vec[q].push_back(p);

	c[p][q] = cpct;
	c[q][p] = cpct;
    }
}

void bfs() {
    int st = 0, dr = 1;

    flux[1] = 2147000000;
    while (st < dr) {
	st++;

	int len = vec[Q[st]].size();
	for (j = 0; j < len; j++) {
	    i = vec[Q[st]][j];
	    if (flux[i] == 0 && c[Q[st]][i]) {
		int x = c[Q[st]][i];
		if (flux[Q[st]] < c[Q[st]][i])
		    x = flux[Q[st]];

		flux[i] = x;
		tata[i] = Q[st];

		Q[++dr] = i;
	    }
	    if (flux[n]) break;
	}
	if (flux[n]) break;
    }

    improve = flux[n];

    if (!improve) return;

    int x = n;
    while (x != 1) {
	c[tata[x]][x] -= flux[n];
	c[x][tata[x]] += flux[n];

	x = tata[x];
    }
}

void dfs(int nod, int tip, int viz) {
    d[nod] = viz;

    int len = vec[nod].size();
    for (int j = 0; j < len; j++) {
	i = vec[nod][j];
	if (tip == 1) {
	    if (c[nod][i] != 0 && !d[i])
		dfs(i, tip, viz);
	}
	else {
	    if (c[i][nod] != 0 && !d[i])
		dfs(i, tip, viz);
	}
    }
}

int main() {

    cit();

    improve = 1;
    while (improve) {
	Q[1] = 1;
	bfs();

	memset(Q, 0, sizeof(Q));
	memset(flux, 0, sizeof(flux));
	memset(tata, 0, sizeof(tata));
    }

    dfs(1, 1, 1);
    dfs(n, 0, 2);

    for (i = 1; i <= n; i++) {
	int len = vec[i].size();
	for (k = 0; k < len; k++) {
	    j = vec[i][k];
	    if (d[i] == 1 && d[j] == 2 && c[i][j] == 0 && c[j][i] != 0)
		sol[++sol[0]] = ind[i][j];
	}
    }

    printf("%d\n", sol[0]);
    for (i = 1; i <= sol[0]; i++)
	printf("%d\n", sol[i]);

    return 0;
}