#include #include #include using namespace std; using namespace atcoder; using mint = modint998244353; #define rep(i,n) for (int i = 0; i < (n); ++i) #define Inf 1000000000 struct HLD{ vector sz,parent,depth,root,pos; vector arr; HLD(vector> &E){ sz.resize(E.size(),1); parent.resize(E.size(),0); depth.resize(E.size(),0); root.resize(E.size(),0); pos.resize(E.size(),0); dfs(0,-1,E); dfs2(0,-1,E,0); } void dfs(int now,int p,vector> &E){ parent[now] = p; if(p==-1){ depth[now] = 0; } else{ depth[now] = depth[p]+1; } for(int i=0;i> &E,int r){ pos[now] = arr.size(); arr.push_back(now); root[now] = r; int maxi = 0; int ind = -1; for(int i=0;i> query(int u,int v){ vector> ret; int t = 0; while(root[u]!=root[v]){ if(depth[root[u]] <= depth[root[v]]){ ret.insert(ret.begin()+t,{pos[root[v]], pos[v]}); v = parent[root[v]]; } else{ ret.insert(ret.begin()+t,{pos[u],pos[root[u]]}); u = parent[root[u]]; t++; } } ret.insert(ret.begin()+t,{pos[u],pos[v]}); return ret; } int lca(int u,int v){ for(;;v=parent[root[v]]){ if(pos[u]>pos[v])swap(u,v); if(root[u]==root[v])return u; } } int get_distance(int u,int v){ return depth[u] + depth[v] - 2 * depth[lca(u,v)]; } }; unsigned long xor128() { static unsigned long x=123456789, y=362436069, z=521288629, w=88675123; unsigned long t=(x^(x<<11)); x=y; y=z; z=w; return (w=(w^(w>>19))^(t^(t>>8))); } int main(){ int N; cin>>N; vector> E(N); vector d(N,0); rep(i,N-1){ int u,v; scanf("%d %d",&u,&v); u--;v--; d[u]++; d[v]++; E[u].push_back(v); E[v].push_back(u); } HLD H(E); vector x; rep(i,N){ if(d[i]==1)x.push_back(i); } rep(_,50){ int a = xor128()%x.size(); int aa = -1; rep(j,x.size()){ if(j==a)continue; int dis = H.get_distance(x[j],x[a]); if(aa==-1)aa= dis; else{ if(aa!=dis){ cout<<"No"<