void build() {
int s = N, t = N + 1;
mf.init( N + 2 );
int v, w, c;
for( int i = 0; i < M; ++i ) {
while( getchar() != '(' );
scanf( "%d", &v );
getchar();
scanf( "%d", &w );
getchar();
scanf( "%d", &c );
mf.insert( v, w, c );
}
for( int i = M; i < M + S; ++i ) {
while( getchar() != '(' );
scanf( "%d", &w );
getchar();
scanf( "%d", &c );
mf.insert( s, w, c );
}
for( int i = M + S; i < M + S + T; ++i ) {
while( getchar() != '(' );
scanf( "%d", &v );
getchar();
scanf( "%d", &c );
mf.insert( v, t, c );
}
}
void build() {
int s = N, t = N + 1;
mf.init( N + 2 );
char skip;
int v, w, c;
for( int i = 0; i < M; ++i ) {
cin >> skip >> v >> skip >> w >> skip >> c;
mf.insert( v, w, c );
}
for( int i = M; i < M + S; ++i ) {
cin >> skip >> w >> skip >> c;
mf.insert( s, w, c );
}
for( int i = M + S; i < M + S + T; ++i ) {
cin >> skip >> v >> skip >> c;
mf.insert( v, t, c );
}
}
int main() {
while( scanf( "%d%d", &N, &M ) && N ) {
mf.init( N + M + 2 );
for( int i = 1; i <= N; ++i ) {
mf.insert( 0, i, 1 );
scanf( "%s", skip );
while( getchar() != '\n' ) {
int x;
scanf( "%d", &x );
mf.insert( i, N + 1 + x, 1 );
}
}
st = mf.edges;
for( int i = 1; i <= M; ++i )
mf.insert( N + i, N + M + 1, N );
ed = mf.edges;
int l = N / M, r = N, m;
while( l < r - 1 ) {
m = ( l + r ) / 2;
if( check( m ) ) r = m;
else l = m;
}
printf( "%d\n", r );
}
}
int main() {
while(scanf("%d%d%d%d", &N, &M, &A, &B) && N) {
mf.init(N);
for(int i = 0; i < M; ++i) {
int x, y, c;
scanf("%d%d%d", &x, &y, &c);
x--;y--;
mf.insert(x, y, c);
mf.insert(y, x, c);
}
puts(mf.uniQ(A-1, B-1) ? "UNIQUE" : "AMBIGUOUS" );
}
}
int main() {
while(cin >> N >> M) {
if(T++) puts("");
int v, w;
double c, m = 0;
mf.init(N);
for(int i = 0; i < M; ++i) {
cin >> v >> w >> c;
m = max(m, c);
mf.insert(v, w, c);
// mf.insert(w, v, c);
}
double l = 0, r = m;
while(r - l > EPS) {
m = (l + r) / 2;
if(check(m)) r = m;
else l = m;
}
/*
for(int i = 0; i < M; ++i) {
cout << mf.buf[i].v << ' ';
cout << mf.buf[i].w << ' ';
cout << mf.buf[i].c << ' ';
cout << mf.buf[i].f << endl;
}
*/
//cout << m << endl;
memset(B, 0, sizeof(B));
EE.clear();
for(int i = 0; i < M; ++i) {
mf.buf[i].c -= m;
if(mf.buf[i].c < 0) EE.push_back(i);
}
dfs(1);puts("");
sort(EE.begin(), EE.end());
EE.resize(unique(EE.begin(), EE.end()) - EE.begin());
cout << EE.size() << endl;
for(int i = 0; i < EE.size(); ++i) {
if(i) cout << ' ';
cout << EE[i] + 1;
}
}
}
bool minCut( double lamda ) {
mf.init( V );
now.clear();
double tot = 0.0;
for( int i = 0; i < EE.size(); ++i ) {
if( EE[i].c > lamda )
mf.insert( EE[i].v-1, EE[i].w-1, EE[i].c - lamda );
else {
now.push_back( i + 1 );
tot += ( EE[i].c - lamda );
}
}
mf.runCut( 0, V - 1 );
eE = mf.getCutE();
for( int i = 0; i < eE.size(); ++i ) {
tot += eE[i] -> c;
now.push_back( eE[i] - &mf.edges()[0] + 1 );
}
sort( now.begin(), now.end() );
ans = now;
return tot < 0.0;
}