#include //using namespace std; #pragma GCC target("avx2") #pragma GCC optimize("O3") #pragma GCC optimize("unroll-loops") #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native") #define rep(i, j, n) for(ll i = ll(j); i < ll(n); i++) #define REP(i, j, n) for(ll i = ll(j); i <= ll(n); i++) #define per(i, j, n) for(ll i = ll(j); ll(n) <= i; i--) #define ALL(a) (a).begin(),(a).end() #define revALL(a) (a).rbegin(),(a).rend() #define pb emplace_back #define mp std::make_pair #define mtp std::make_tuple #define ln "\n" using std::endl; using std::cin; using std::cout; using ll = long long; using lint = __int128; using std::vector; using std::string; using std::upper_bound; using std::lower_bound; using vi = vector; using vii = vector; using pii = std::pair; using vs = vector; using vss = vector; using pss = std::pair; using vl = vector; using vll = vector; using pll = std::pair; //constexpr ll MOD = 1e9+7, root = 0; // constexpr ll MOD = 998244353, root = 3; //constexpr ll MOD = 924844033, root = 5; //constexpr ll MOD = 1e4, root = 0; //constexpr ll MOD = 1e5, root = 0; //constexpr ll MOD = 1e6, root = 0; //constexpr ll MOD = 1e7, root = 0; constexpr ll MAX = 1e6+10; constexpr ll inf = (1ll << 60); constexpr lint linf = lint(inf) * inf; //lint output void lout(lint N, string add){ string S; if(N < 0){ S += '-'; N = -N; } string T; if(N == 0) T += '0'; while(N){ T += N % 10 + '0'; N /= 10; } reverse(ALL(T)); S += T; cout << S << add; } //lint input lint lin(){ string S; cin >> S; bool flag = 0; if(S[0] == '-') flag = 1; lint ret = 0; rep(i, flag, S.size()) ret = ret * 10 + S[i] - '0'; if(flag) ret *= -1; return ret; } //reversed priority_queue template class prique :public std::priority_queue, std::greater> {}; //modpow ll modpow(ll X, ll Y, ll mod){ ll ret = 1; while(Y){ if(Y & 1){ ret *= X; ret %= mod; } X *= X; X %= mod; Y >>= 1; } return ret % mod; } //calc: ax + by = gcd(a, b) template void extGCD(ll a, ll b, T &x, T &y){ if(b == 0){ x = 1; y = 0; return; } extGCD(b, a%b, y, x); /*(a-b)x + by = gcd(a,b) ax + b(y-x) = gcd(a,b)*/ y -= a / b * x; } //calc: ax + by = c template bool solve_equation(ll a, ll b, ll c, T &x, T &y){ ll d = std::__gcd(a, b); if(c % d) return false; extGCD(a, b, x, y); ll e = a * b / d; x %= e; y %= e; x = (lint)x * (c/d) % e; y = (lint)y * (c/d) % e; return true; } //segment_tree, 1-indexed template struct segment_tree{ ll N; T INF; vector node; segment_tree(vector &X, T INF_):INF(INF_){ N = 1; while(N < X.size()) N <<= 1; node.resize(2*N, INF); rep(i, 0, X.size()) node[N+i] = X[i]; per(i, N-1, 0) node[i] = compare(node[i*2], node[i*2+1]); } T compare(T A, T B){ return std::max(A, B); } //for max_right, min_left //compare をいじった時にはこちらも変えた方がよい bool is_lower(T A, T B){ return A < B; } //isAdd == true: add //isAdd == false: update void update(ll index, T val, bool isAdd){ index += N; if(isAdd) node[index] += val; else node[index] = val; while(index > 0){ index >>= 1; node[index] = compare(node[index*2], node[index*2+1]); } } T calc(ll left, ll right){ T ret = INF; left += N; right += N; while(left < right){ if(left & 1) ret = compare(node[left++], ret); if(right & 1) ret = compare(node[--right], ret); left >>= 1; right >>= 1; } return ret; } //[left, inf) ll min_left(ll left, T val, ll now = 1, ll l = 0, ll r = -1){ if(r < 0) r = N; if(is_lower(node[now], val) || r<=left) return r; if(N <= now) return l; ll vl = min_left(left, val, now*2, l, (l+r)/2); if(vl == (l+r)/2) return min_left(left, val, now*2+1, (l+r)/2, r); return vl; } //(-inf, right] //内部では (-inf, right+1) ll max_right(ll right, T val, ll now = 1, ll l = 0, ll r = -1){ if(r < 0) r = N, right++; if(is_lower(node[now], val) || right<=l) return l-1; if(N <= now) return l; ll vr = max_right(right, val, now*2+1, (l+r)/2, r); if(vr == (l+r)/2-1) return max_right(right, val, now*2, l, (l+r)/2); return vr; } }; //lazy_segment_tree template struct lazy_segment_tree{ int N, height; vector node, lazy; T valINF, lazyINF; lazy_segment_tree(vector X, T valINF_, T lazyINF_) : valINF(valINF_), lazyINF(lazyINF_){ N = 1, height = 0; while(N < X.size()) N <<= 1, height++; node.resize(2*N, valINF); lazy.resize(2*N, lazyINF); rep(i, 0, X.size()) node[i+N] = X[i]; per(i, N-1, 0) node[i] = compare(node[i*2], node[i*2+1]); } void add(ll left, ll right, T val){ ll l = left+N, r = right+N; ll L = l, R = r; per(i, height, 0){ eval(l >> i); eval(r >> i); } while(l < r){ if(l & 1){ addition(lazy[l], val); l++; } if(r & 1){ r--; addition(lazy[r], val); } l >>= 1; r >>= 1; } while(L){ if(lazy[L]==lazyINF && L>= 1; R >>= 1; } } T calc(ll left, ll right){ ll l = left+N, r = right+N; per(i, height, 0){ eval(l >> i); eval(r >> i); } T ret = valINF; while(l < r){ if(l & 1){ eval(l); ret = compare(node[l], ret); l++; } if(r & 1){ r--; eval(r); ret = compare(node[r], ret); } l >>= 1; r >>= 1; } return ret; } //[left, inf) ll min_left(ll left, T val, ll now = 1, ll l = 0, ll r = -1){ if(r < 0) r = N; eval(now); if(is_lower(node[now], val) || r<=left) return r; if(N <= now) return l; ll vl = min_left(left, val, now*2, l, (l+r)/2); if(vl == (l+r)/2) return min_left(left, val, now*2+1, (l+r)/2, r); return vl; } //(-inf, right] //内部では (-inf, right+1) ll max_right(ll right, T val, ll now = 1, ll l = 0, ll r = -1){ if(r < 0) r = N, right++; eval(now); if(is_lower(node[now], val) || right<=l) return l-1; if(N <= now) return l; ll vr = max_right(right, val, now*2+1, (l+r)/2, r); if(vr == (l+r)/2-1) return max_right(right, val, now*2, l, (l+r)/2); return vr; } private: T compare(T A, T B){ return std::max(A, B); } //for max_right, min_left //compare をいじった時にはこちらも変えた方がよい bool is_lower(T A, T B){ return A < B; } void addition(T &A, T B){ //addition : A += B; //update : A = B; } void eval(int now){ if(lazy[now] == lazyINF) return; if(now < N){ addition(lazy[now*2], lazy[now]); addition(lazy[now*2+1], lazy[now]); } addition(node[now], lazy[now]); lazy[now] = lazyINF; } }; //union_find_tree struct union_find{ ll N; vi par, siz; union_find(int n) : N(n){ par.resize(N); siz.resize(N, 1); rep(i,0,N) par[i] = i; } ll root(ll X){ if(par[X] == X) return X; return par[X] = root(par[X]); } bool same(ll X, ll Y){ return root(X) == root(Y); } void unite(ll X, ll Y){ X = root(X); Y = root(Y); if(X == Y) return; if(siz[Y] < siz[X]) std::swap(X, Y); par[X] = Y; siz[Y] += siz[X]; siz[X] = 0; } ll size(ll X){ return siz[root(X)]; } }; //binary_indexed_tree template struct binary_indexed_tree{ int N; vector bit; binary_indexed_tree(int n):N(n){ bit.resize(N+1,0); } T addition(T a, T b){ return a+b; } void add(int x,T a){ x++; for(x; x<=N; x+=(x&-x)) bit[x] = addition(bit[x], a); } T sum(int x){ x++; T ret=0; for(x; x>0; x-=(x&-x)) ret = addition(ret, bit[x]); return ret; } ll lower_bound(T X){ if(sum(N) que; rep(i,0,N){ if(cnt[i] == 0) que.push(i); } while(!que.empty()){ ll now = que.front(); que.pop(); ret.pb(now); for(auto next:edge[now]){ cnt[next]--; if(cnt[next] == 0) que.push(next); } } return ret; } vii SCC(){ vii revedge(N), ver; vi ind(N); rep(i,0,N){ for(auto p:edge[i]) revedge[p].pb(i); } vi num(N, -1), po(N); vector seen(N); ll cnt = 0; rep(i,0,N){ if(num[i] == -1){ dfs(i, num, cnt); } } rep(i,0,N) po[num[i]] = i; per(i,N-1,0){ ll X = po[i]; if(!seen[X]){ std::queue que; vi v; que.push(X); seen[X] = 1; while(!que.empty()){ ll now = que.front(); que.pop(); v.pb(now); ind[now] = ver.size(); for(auto p:revedge[now]){ if(!seen[p]){ seen[p] = 1; que.push(p); } } } ver.pb(v); } } return ver; } void dfs(ll now, vi &num, ll &cnt){ num[now] = 0; for(auto next:edge[now]){ if(num[next] == -1){ dfs(next, num, cnt); } } num[now] = cnt++; } }; //sparse_table template struct sparse_table{ ll N; T INF; vector A; vi mem; vector> table; std::function compare; sparse_table(vector X, T INF_, std::function compare_) : A(X), INF(INF_), compare(compare_){ N = A.size(); mem.resize(N+1, -1); int height = 0; while((1<(height, INF)); rep(i,0,N) table[i][0] = A[i]; rep(j,1,height){ rep(i,0,N){ table[i][j] = compare(table[i][j-1], table[std::min(N-1, i+(1ll<<(j-1)))][j-1]); } } REP(i,1,N){ mem[i] = std::max(mem[i-1], mem[i]); } } //[l, r) T calc(ll l, ll r){ ll width = r-l; return compare(table[l][mem[width]], table[r-(1< que; que.push(0); while(!que.empty()){ int now=que.front(); que.pop(); for(int i=0;i>=1; } } if(X==Y) return X; for(int i=19;i>=0;i--){ if(dp[X][i]!=dp[Y][i]){ X=dp[X][i]; Y=dp[Y][i]; } } return dp[X][0]; } void Subtree(){ subtree.resize(N,-1); dfs(0); } void dfs(ll now){ subtree[now]=1; for(auto next:edge[now]){ if(subtree[next]==-1){ dfs(next); subtree[now]+=subtree[next]; } } } }; //max_flow template struct max_flow{ struct Edge{ int to; T cap; int rev; }; int N; vector> edge; vector dist,itr; max_flow(vii e,vii w){ N=e.size(); edge.resize(N); rep(i,0,N){ rep(j,0,e[i].size()){ edge[i].pb((Edge){(int)e[i][j],(T)w[i][j],(int)edge[e[i][j]].size()}); edge[e[i][j]].pb((Edge){i,0,(int)edge[i].size()-1}); } } } void add_edge(int from,int to,T cap){ edge[from].pb((Edge){to,cap,(int)edge[to].size()}); edge[to].pb((Edge){from,0,(int)edge[from].size()-1}); } void bfs(int s){ dist.assign(N,-1); std::queue que; dist[s]=0; que.push(s); while(!que.empty()){ int now=que.front(); que.pop(); for(auto p:edge[now]){ int next=p.to; if(p.cap>0&&dist[next]<0){ dist[next]=dist[now]+1; que.push(next); } } } } T dfs(int now,int t,T f){ if(now==t) return f; for(;itr[now]0&&dist[now]0){ p.cap-=mem; edge[p.to][p.rev].cap+=mem; return mem; } } } return 0; } T Query(int s,int t){ T ret=0; while(1){ bfs(s); if(dist[t]<0) break; itr.assign(N,0); while(1){ int mem=dfs(s,t,(1<<30)); if(mem<=0) break; ret+=mem; } } return ret; } }; //min_cost_flow struct min_cost_flow{ struct Edge{ int to,cap,rev; ll cost; }; int N; vector> edge; vector dist,h; void add_edge(int from,int to,int cap,ll cost){ edge[from].pb((Edge){to,cap,(int)edge[to].size(),cost}); edge[to].pb((Edge){from,0,(int)edge[from].size()-1,-cost}); } min_cost_flow(vii e,vii m,vii w){ N=e.size(); edge.resize(N); rep(i,0,N){ rep(j,0,e[i].size()){ add_edge(i,e[i][j],m[i][j],w[i][j]); } } } void potential(){ h.assign(N,0); vector> edge2(N); vii weight(N); vector cnt(N); rep(i,0,N){ for(auto e:edge[i]){ if(e.cap>0&&e.cost<0){ edge2[i].pb(e.to); weight[i].pb(-e.cost); cnt[e.to]++; } } } std::queue que; rep(i,0,N){ if(cnt[i]==0) que.push(i); } vector ver; while(!que.empty()){ int now=que.front(); que.pop(); ver.pb(now); for(auto next:edge2[now]){ cnt[next]--; if(cnt[next]==0) que.push(next); } } per(i,N-1,0){ rep(j,0,edge2[ver[i]].size()){ int next=edge2[ver[i]][j]; h[ver[i]]=std::max(h[ver[i]],h[next]+weight[ver[i]][j]); } } } ll Query(int s,int t,int f){ ll ret=0; potential(); while(f){ vi dist(N,inf); vector memv(N),meme(N); dist[s]=0; prique> que; que.push(mp(0,s)); while(!que.empty()){ auto now=que.top().second; if(dist[now]0&&dist[next]>dist[now]+h[now]-h[next]+e.cost){ dist[next]=dist[now]+h[now]-h[next]+e.cost; memv[next]=now; meme[next]=i; que.push(mp(dist[next],next)); } } } if(dist[t]==inf) return -1; int now=t,max=f; while(now!=s){ auto& e=edge[memv[now]][meme[now]]; max=std::min(max,e.cap); now=memv[now]; } f-=max; now=t; while(now!=s){ auto& e=edge[memv[now]][meme[now]]; e.cap-=max; auto& e2=edge[e.to][e.rev]; e2.cap+=max; now=memv[now]; } rep(i,0,N) h[i]+=dist[i]; ret+=h[t]*max; } return ret; } }; //fft struct Fast_Fourier_Transform{ void dft(vector> &func,int inverse){ int siz=func.size(); if(siz==1) return; vector> left,right; rep(i,0,siz/2){ left.pb(func[i*2]); right.pb(func[i*2+1]); } dft(left,inverse); dft(right,inverse); std::complex now=1,zeta=std::polar(1.0,inverse*2.0*acos(-1)/siz); rep(i,0,siz){ func[i]=left[i%(siz/2)]+now*right[i%(siz/2)]; now*=zeta; } } template vector multiply(vector f,vector g){ vector> nf,ng; int siz=1; while(siz ret(siz); rep(i,0,siz) ret[i]=nf[i].real()/siz; return ret; } }; //ntt struct Numver_Theoretic_Transform{ vii mem; Numver_Theoretic_Transform(void){ mem.resize(25,vi(2)); rep(i,0,25){ mem[i][1]=modpow(root,MOD-1-(MOD-1)/(1< cnt; vector> next; Trie(int element,char low):let(element),lower(low){ cnt.resize(1); next.pb(vector(let,-1)); } void insert(string S){ int now=0; for(auto s:S){ int X=s-lower; if(next[now][X]==-1){ next[now][X]=cnt.size(); cnt.pb(0); next.pb(vector(lower,-1)); } now=next[now][X]; } cnt[now]++; } int get(string S){ int now=0; for(auto s:S){ int X=s-lower; if(next[now][X]==-1) return 0; now=next[now][X]; } return cnt[now]; } }; //point template struct point{ T x,y; void operator+=(const point &other){ x += other.x; y += other.y; } void operator-=(const point &other){ x -= other.x; y -= other.y; } bool operator<(const point &other){ if(x == other.x) return y < other.y; return x < other.x; } bool operator==(const point &other){ return x==other.x && y==other.y; } }; //偏角の比較を整数で template struct tancomp{ int place(point p){ if(p.x<=0&&p.y<0) return 0; if(p.x>0&&p.y<=0) return 1; if(p.x==0&&p.y==0) return 2; if(p.x>=0&&p.y>0) return 3; return 4; } bool operator()(const point &l,const point &r){ if(place(l)!=place(r)) return place(l) vi convex_hull(vector> A){ ll N = A.size(); vector,ll>> data(N); rep(i,0,N) data[i] = mp(A[i],i); sort(ALL(data),[](std::pair,ll> l,std::pair,ll> r){ if(l.first == r.first) return l.second < r.second; return l.first < r.first; }); vi ret; ret.pb(0); //lower rep(i,1,data.size()){ while(ret.size() > 1){ ll n = ret.size(); point A = data[ret[n-2]].first; point B = data[ret[n-1]].first; point C = data[i].first; B -= A; C -= A; if(B.x*C.y-B.y*C.x < 0) ret.pop_back(); else break; } ret.pb(i); } //upper per(i,int(data.size())-2,0){ while(ret.size() > 1){ ll n = ret.size(); point A = data[ret[n-2]].first; point B = data[ret[n-1]].first; point C = data[i].first; B -= A; C -= A; if(B.x*C.y-B.y*C.x < 0) ret.pop_back(); else break; } ret.pb(i); } ret.pop_back(); for(auto &p:ret) p = data[p].second; return ret; } //binom_init, binom vi fac,finv,inv; void binom_init() { fac.resize(MAX); finv.resize(MAX); inv.resize(MAX); fac[0] = fac[1] = 1; inv[1] = 1; finv[0] = finv[1] = 1; rep(i, 2, MAX){ fac[i] = fac[i-1]*i%MOD; inv[i] = MOD-MOD/i*inv[MOD%i]%MOD; finv[i] = finv[i-1]*inv[i]%MOD; } } ll binom(ll n, ll r){ if(n memo; rep(i,0,A.size()) memo[A[i]]=0; ll cnt=0; for(auto &p:memo) p.second=cnt++; rep(i,0,A.size()) A[i]=memo[A[i]]; } //decrease the value of map void dec(std::map &mem,ll X){ mem[X]--; if(mem[X]==0) mem.erase(X); } ll N; vii edge; vi dp; ll ans = 0; void dfs(ll now){ dp[now]++; for(auto next:edge[now]){ if(dp[next] == 0){ dfs(next); dp[now] += dp[next]; ans += dp[next]*(N-dp[next]); ans %= MOD; } } } //main int main(){ std::ios::sync_with_stdio(false); std::cin.tie(nullptr); std::cout.tie(nullptr); std::random_device rnd; std::mt19937 mt(rnd()); cin >> N; edge.resize(N); dp.resize(N); rep(i,1,N){ ll X,Y; cin >> X >> Y; edge[--X].pb(--Y); edge[Y].pb(X); } dfs(0); ans *= modpow(N*(N-1)/2%MOD*(N-1)%MOD,MOD-2,MOD); ans %= MOD; ans = 1-ans; if(ans < 0) ans += MOD; cout << ans << ln; }