#include <iostream> #include <cstdio>#include <cstring>#include <queue>#include <algorithm>using namespace std;const double oo = 1e20;const int MAXN = 310;const double eps = 1e-9;struct Edge { int s, e, nx, id;double c;Edge(int a , int b, double d): s(a), e(b), c(d) {}Edge() {}}E[5010], E1[5010];int head[MAXN], cnt;void add(int s, int e, int id, double c) {E[cnt].s = s; E[cnt].e = e; E[cnt].c = c; E[cnt].id = id; E[cnt].nx = head[s]; head[s] = cnt++; swap(s,e); E[cnt].s = s; E[cnt].e = e; E[cnt].c = c; E[cnt].id = id; E[cnt].nx = head[s]; head[s] = cnt++;}int d[MAXN], num[MAXN], Stack[MAXN], Top, H[MAXN];int sgn(double x) {return x < -eps ? -1 : x > eps;}double isap(int N, int s, int t) { memset(d, 0, sizeof(d)); memset(num, 0, sizeof(num)); num[0] = N; double ans = 0; for(int i = 0; i <= N; i++) { H[i] = head[i]; } Top = 0; int x; while(d[s] < N) { if(!Top) {x = s;} else {x = E[Stack[Top - 1]].e;}if(x == t) { double p = E[Stack[0]].c; for(int i = 1; i < Top; i++) { p = min(p, E[Stack[i]].c);} ans += p; for(int i = Top - 1; i >= 0; i--) { E[Stack[i]].c -= p; if(E[Stack[i]].c == 0) {Top = i;} E[Stack[i]^1].c += p; }} else {for(int i = H[x]; ~i; i = E[i].nx) {if(E[i].c > 0 && d[E[i].e] == d[x] - 1) { Stack[Top ++] = i; H[x] = i; goto nx;}}if(--num[d[x]] == 0) {return ans;}int mi = N;for(int i = head[x]; ~i; i = E[i].nx) { if(E[i].c > 0 && mi > d[E[i].e]) { mi = d[E[i].e]; H[x] = i; }}d[x] = mi + 1;num[d[x]]++;if(x != s) {Top--;}} nx:; }return ans;} int n, m;double judge(double x) {memset(head, -1, sizeof(head));cnt = 0;double ans = 0.0;for(int i = 1; i <= m; i++) {int u = E1[i].s, v = E1[i].e;double w = E1[i].c;if(sgn(w - x) >= 0) {add(u, v, i, w - x);}else {ans -= (x - w);}}ans += isap(n + 5, 1, n);return ans;}int mark[500];bool vst[500];queue<int> Q;void bfs(int st, int id) {while(!Q.empty()) {Q.pop();}mark[st] = id;Q.push(st);vst[st] = 1;while(!Q.empty()) {int u = Q.front(); Q.pop();for(int i = head[u]; ~i; i = E[i].nx) {int v = E[i].e;double c = E[i].c;if(c > 0 && vst[v] == 0) {vst[v] = 1;Q.push(v);mark[v] = id;}}}}int ans[500], tot;void gao(double dis) {memset(mark, 0, sizeof(mark));memset(vst, 0, sizeof(vst));bfs(1, 1);tot = 0;for(int i = 0; i < cnt; i++) {int u = E[i].s, v = E[i].e, id = E[i].id;if(i % 2 == 0 && mark[u] != mark[v]) {ans[++tot] = id;}}for(int i = 1; i <= m; i++) {if(sgn(E1[i].c - dis) < 0) {ans[++tot] = i;}}sort(ans + 1, ans + tot + 1);printf("%dn", tot);for(int i = 1; i <= tot; i++) {printf("%d%c", ans[i], (i == tot) ? 'n' : ' ');}}int main() {int cas = 0;while(~scanf("%d%d", &n, &m)) {cas++;if(cas != 1) {puts("");}double L, R;L = R = 0;for(int i = 1; i <= m; i++) {int u, v, w;scanf("%d%d%d", &u, &v, &w);E1[i] = Edge(u, v, w);R += w;}for(int i = 1; i <= 100; i++) {double m = (L + R) / 2;double tmp = judge(m);if(sgn(tmp) > 0) {L = m + eps;}else {R = m;}}judge(R);gao(L);}return 0;}
