#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;} //------------------------------------------------------- template class UF { public: vector par,rank,cnt; UF() {par=rank=vector(um,0); cnt=vector(um,1); for(int i=0;irank[y]) return par[x]=y; rank[x]+=rank[x]==rank[y]; return par[y]=x; } }; UF<101010> uf; int N; int A[101010],B[101010]; vector> E[101010]; vector lp; int C[101010]; int ret[101010]; void dfs(int cur,int pre) { FORR2(e,i,E[cur]) { if(e==pre) { ret[i]=cur; } else { dfs(e,cur); } } } void solve() { int i,j,k,l,r,x,y; string s; cin>>N; FOR(i,N) { cin>>A[i]>>B[i]; A[i]--,B[i]--; if(uf[A[i]]==uf[B[i]]) { lp.push_back(i); } else { uf(A[i],B[i]); E[A[i]].push_back({B[i],i}); E[B[i]].push_back({A[i],i}); } } FOR(i,N) { C[uf[A[i]]]++; C[uf[B[i]]]++; } FOR(i,N) if(uf[i]==i && C[i]!=uf.count(i)*2) return _P("No\n"); FORR(c,lp) { ret[c]=A[c]; dfs(A[c],A[c]); } cout<<"Yes"<