#qlude <bits/stdc++.h>

using namesace std;

vector<int> a[1002];
int c[1002][1002];
int f[1002][1002];
int co[1002];
int is[2][1002];
int sol[10002];
int vizitat[1002];
int st[10002];
int dr[10002];
int t[1002];
int N,M;

int bfs()
{
    int i,x,y,q,sf;

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

    return t[N];
}

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

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

int main(){
ifstream f("critice.in");
ofstream g("critice.out");
    int i,j,x,y,z,r,cnt=0;

    f>>N>>M;
    for(i = 1; i <= M; ++i)
    {
       f>>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;
            }
        }

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

    g<<cnt<<"\n";;
    for(i = 1; i <= M; ++i)
        if(sol[i]) g<<i<<"\n";


}