求调样例不对结果ac

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define PII pair<int,int>
#define cy cout<<"YES"<<endl
#define cn cout<<"NO"<<endl
#define l(rt) rt<<1
#define r(rt) rt<<1|1
const int N=3e5+6,yyx=4e9+7;
int n,k,pre[N],st[N];
vector<PII> to[N];
bool check(int x){
    //memset(st,0,sizeof st);
    set<int> s;
    for(int i=1;i<=n;++i){
        for(auto c:to[i]){
            int j=c.first,w=c.second;
            if(x>=w) s.insert(j);
        }
    }
    int ans=s.size();
    //cout<<ans<<" "<<x<<endl;
    if(ans>=n) return 1;
    return 0;
}
void solve(){
  cin>>n>>k;
  for(int i=1;i<=k;++i){
    int x,y,t;cin>>x>>y>>t;
    to[x].push_back({y,t});
    to[y].push_back({x,t});
  }
  int l=0,r=1e5+1;
  while(l+1<r){
    int m=l+r>>1;
    if(check(m)) r=m;
    else l=m;
  }
  if(!l||r==1e5+1) cout<<-1<<endl;
  else cout<<r<<endl;
}
signed main(){
    cin.tie(0)->sync_with_stdio(0);
    int _=1;
    //cin>>_;
    while(_--)
    solve();
    return 0;
}