/**
 *  Muchiile critice sunt muchiile saturate care sunt accesibile din sursa si din destinatie doar pe muchii nesaturate ;)
 *
 */
#include <fstream>
#include <vector>
#include <bitset>
#include <queue>
#include <algorithm>
#include <utility>
#include <cstring>
#include <string>
#include <stack>
#include <deque>
#include <iomanip>
#include <set>
#include <map>
#include <cassert>
#include <ctime>
#include <list>
#include <iomanip>

using namespace std;

string file = "critice";

ifstream cin( (file + ".in").c_str() );
ofstream cout( (file + ".out").c_str() );

const int MAXN = 1005;
const int MAXM = 10005;
const int oo = 0x3f3f3f3f;

typedef vector<int> Graph[MAXN];
typedef vector<int> :: iterator It;

const inline int min(const int &a, const int &b)  { if( a > b ) return b;   return a; }
const inline int mabs(const int a)                { if( a > 0 ) return a;   return -a; }
const inline int max(const int &a, const int &b)  { if( a < b ) return b;   return a; }
const inline void Get_min(int &a, const int b)    { if( a > b ) a = b; }
const inline void Get_max(int &a, const int b)    { if( a < b ) a = b; }

struct ClassComp {
    inline bool operator () (const int &a, const int &b) const {
        return a > b;
    }
};

int N, M, Father[MAXN], C[MAXN][MAXN], F[MAXN][MAXN];
Graph G;
vector<pair<int, int> > Edge;
queue <int> Q, Critics;
bitset <MAXN> Vis, Source, Sink;

inline bool BFs() {
    int Node = 1;
    Vis.reset();
    for(Q.push(Node), Vis[Node] = true ; !Q.empty() ; Q.pop(), Node = Q.front())
        for(It it = G[Node].begin(), fin = G[Node].end(); it != fin ; ++ it)
            if(!Vis[*it] && C[Node][*it] != F[Node][*it])
                Vis[*it] = true, Q.push(*it), Father[*it] = Node;
    return Vis[N];
}

inline void BFs(int Node, bitset <MAXN> & Viz) {
    for(Q.push(Node), Viz[Node] = true ; !Q.empty() ; Q.pop(), Node = Q.front())
        for(It it = G[Node].begin(), fin = G[Node].end(); it != fin ; ++ it)
            if(!Viz[*it] && C[Node][*it] != mabs(F[Node][*it]) )
                Viz[*it] = true, Q.push(*it), Father[*it] = Node;
}

int main() {
    cin >> N >> M;
    for(int i = 1 ; i <= M ; ++ i) {
        int x, y, z;
        cin >> x >> y >> z;
        Edge.push_back(make_pair(x, y));
        G[x].push_back(y);
        G[y].push_back(x);
        C[x][y] = z;
        C[y][x] = z;
    }
    for( ; BFs() ; )
        for(It it = G[N].begin(), fin = G[N].end(); it != fin ; ++ it) {
            int Node = *it;
            if(C[Node][N] == F[Node][N] || !Vis[N])
                continue;
            int minFlow = oo;
            for(int i = N ; i != 1 ; i = Father[i])
                minFlow = min(minFlow, C[Father[i]][i] - F[Father[i]][i]);
            for(int i = N ; i != 1 ; i = Father[i])
                F[Father[i]][i] += minFlow,
                F[i][Father[i]] -= minFlow;
        }
    BFs(1, Source);
    BFs(N, Sink);
    for(int i = 0 ; i < Edge.size() ; ++ i) {
        int x = Edge[i].first;
        int y = Edge[i].second;
        if(C[x][y] == F[x][y] || C[y][x] == F[y][x])
            if((Source[x] && Sink[y]) || (Source[y] && Sink[x]))
                Critics.push(i + 1);
    }
    for( cout << Critics.size() << '\n' ; !Critics.empty() ; Critics.pop() )
        cout << Critics.front() << '\n';
    cin.close();
    cout.close();
    return 0;
}