#include <fstream>

#include <vector>

#include <queue>

#include <algorithm>



using namespace std;



ifstream f ( "critice.in" );

ofstream g ( "critice.out" );



const int N = 1001;

vector < pair < int, int > > graph[N];

queue < int > q;

int C[N][N], F[N][N], sol[N], tata[N];

bool viz[N], viz1[N], muchie[N];

int n;



bool bfs ( int start ){

    for ( int i = 1; i <= n; i++ )

        viz[i] = tata[i] = 0;

    viz[start] = 1;

    q.push ( start );

    while ( !q.empty ( ) ){

        int node = q.front ( );

        q.pop ( );

        for ( int i = 0; i < graph[node].size ( ); i++ ){

            int new_node = graph[node][i].first;

            if ( viz[new_node] == 0 && F[node][new_node] < C[node][new_node] ){

                viz[new_node] = 1;

                q.push ( new_node );

                tata[new_node] = node;

            }

        }

    }

    return viz[n];

}



void bfs2 ( int start ){

    viz1[start] = 1;

    q.push ( start );

    while ( !q.empty ( ) ){

        int node = q.front ( );

        q.pop ( );

        for ( int i = 0; i < graph[node].size ( ); i++ ){

            int new_node = graph[node][i].first;

            if ( viz1[new_node] == 0 && F[new_node][node] < C[new_node][node] ){

                viz1[new_node] = 1;

                q.push ( new_node );

            }

        }

    }

}



int main()

{   int m, i, x, y, k = 0, z;

    f >> n >> m;

    for ( i = 1; i <= m; i++ ){

        f >> x >> y >> z;

        C[x][y] = z;

        if ( ! ( x == 1 || y == 1 || x == n || y == n ) )

            C[y][x] = z;

        graph[x].push_back ( { y, i } );

        graph[y].push_back ( { x, i } );

    }

    while ( bfs ( 1 ) == 1 ){

        for ( i = 0; i < graph[n].size ( ); i++ ){

            int node = graph[n][i].first;

            if ( viz[node] == 0 || F[node][n] == C[node][n] )

                continue;

            int Min = C[node][n] - F[node][n];

            while ( node != 1 ){

                Min = min ( Min, C[tata[node]][node] - F[tata[node]][node] );

                node = tata[node];

            }

            node = graph[n][i].first;

            F[node][n] += Min;

            F[n][node] -= Min;

            while ( node != 1 ){

                F[tata[node]][node] += Min;

                F[node][tata[node]] -= Min;

                node = tata[node];

            }

        }

    }

    bfs2 ( n );

    for ( i = 1; i <= n; i++ ){

        for ( int j = 0; j < graph[i].size ( ); j++ ){

            int node = graph[i][j].first;

            int ang = graph[i][j].second;

            if ( ( ( viz[i] == 1 && viz1[node] == 1 ) || ( viz1[i] == 1 && viz[node] == 1 ) ) && muchie[ang] == 0 ){

                sol[++k] = graph[i][j].second;

                muchie[ang] = 1;

            }

        }

    }

    g << k << '\n';

    for ( i = 1; i <= k; i++ )

        g << sol[i] << '\n';

    return 0;

}