#include //#include //#include //#include #define rep(i, a) for (int i = (int)0; i < (int)a; ++i) #define rrep(i, a) for (int i = (int)a - 1; i >= 0; --i) #define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i) #define RREP(i, a, b) for (int i = (int)a - 1; i >= b; --i) #define repl(i, a) for (ll i = (ll)0; i < (ll)a; ++i) #define pb push_back #define eb emplace_back #define all(x) x.begin(), x.end() #define rall(x) x.rbegin(), x.rend() #define popcount __builtin_popcount #define popcountll __builtin_popcountll #define fi first #define se second using ll = long long; constexpr ll mod = 1e9 + 7; constexpr ll mod_998244353 = 998244353; constexpr ll INF = 1LL << 60; // #pragma GCC target("avx2") // #pragma GCC optimize("O3") // #pragma GCC optimize("unroll-loops") //using lll=boost::multiprecision::cpp_int; //using Double=boost::multiprecision::number>;//仮数部が1024桁 template inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; } template inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; } ll mypow(ll x, ll n, const ll &p = -1) { //x^nをmodで割った余り if (p != -1) { x =(x%p+p)%p; } ll ret = 1; while (n > 0) { if (n & 1) { if (p != -1) ret = (ret * x) % p; else ret *= x; } if (p != -1) x = (x * x) % p; else x *= x; n >>= 1; } return ret; } using namespace std; //using namespace atcoder; struct edge{ int to,cost; edge(int a,int b):to(a),cost(b){} }; void solve() { int n,m; cin>>n>>m; vector>g(n); int maxv=0; rep(i,m){ int s,t,d; cin>>s>>t>>d; s--;t--; g[s].eb(t,d); g[t].eb(s,d); chmax(maxv,d); } int l=0,r=maxv+1; auto dfs=[&g](auto self,int w,int v,vector &ok)->void{ ok[v]=true; for(auto x:g[v]){ if(!ok[x.to]&&w<=x.cost){ self(self,w,x.to,ok); } } }; while(r-l>1){ int mid=(l+r)/2; vectorok(n); dfs(dfs,mid,0,ok); if(ok.back()){ l=mid; }else{ r=mid; } } int w=l; vectordis(n,-1); dis[0]=0; queueq; q.emplace(0); while(!q.empty()){ int v=q.front(); q.pop(); for(auto x:g[v]){ if(dis[x.to]==-1&&x.cost>=w){ dis[x.to]=dis[v]+1; q.emplace(x.to); } } } int min_dis=dis.back(); cout<