#include using namespace std; typedef signed long long ll; #define _P(...) (void)printf(__VA_ARGS__) #define FOR(x,to) for(x=0;x<(to);x++) #define FORR(x,arr) for(auto& x:arr) #define FORR2(x,y,arr) for(auto& [x,y]:arr) #define ALL(a) (a.begin()),(a.end()) #define ZERO(a) memset(a,0,sizeof(a)) #define MINUS(a) memset(a,0xff,sizeof(a)) template bool chmax(T &a, const T &b) { if(a bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;} //------------------------------------------------------- int N; vector E[202020]; set D; void dfs(int cur,int pre,int d) { if(E[cur].size()==1) D.insert(d); else { FORR(e,E[cur]) if(e!=pre) dfs(e,cur,d+1); } } void solve() { int i,j,k,l,r,x,y; string s; cin>>N; FOR(i,N-1) { cin>>x>>y; E[x-1].push_back(y-1); E[y-1].push_back(x-1); } x=-1; FOR(i,N) if(E[i].size()>2) { if(x==-1) x=i; else return _P("No\n"); } if(x==-1) return _P("No\n"); FORR(e,E[x]) dfs(e,x,1); if(D.size()==1) { cout<<"Yes"<