#include <bits/stdc++.h>
                                                #include<iostream>
                                                #include<cstdio>
                                                #include<vector>
                                                #include<queue>
                                                #include<map>
                                                #include<cstring>
                                                #include<string>
                                                #include <math.h>
                                                #include<algorithm>
                                            //    #include <boost/multiprecision/cpp_int.hpp>
                                                #include<functional>
                               	       #define int long long
                                                #define inf  1000000007
                                              #define pa pair<int,int>
                                               #define pad pair<double,double>
                                                #define ll long long
                                                #define pal pair<double,double>
                                                #define ppap pair<pa,int>
                                          #define PI 3.14159265358979323846
                                                #define paa pair<pa,pa>
                                                #define  mp make_pair
                                                #define  pb push_back
                                                #define EPS (1e-10)
                                                #define equals(a,b) (fabs((a)-(b))<EPS)
                                            //    #define double long double
        int dx[4]={0,-1,0,1};
        int dy[4]={1,0,-1,0};
                                                using namespace std;
                                       			class pa3{
                                                	public:
                                                	int x,y,z;
                                                	pa3(int x=0,int y=0,int z=0):x(x),y(y),z(z) {}
                                                	bool operator < (const pa3 &p) const{
                                                		if(x!=p.x) return x<p.x;
                                                		if(y!=p.y) return y<p.y;
                                                		 return z<p.z;
                                                		//return x != p.x ? x<p.x: y<p.y;
                                                	}
                                       				bool operator > (const pa3 &p) const{
                                                		if(x!=p.x) return x>p.x;
                                                		if(y!=p.y) return y>p.y;
                                                		 return z>p.z;
                                                		//return x != p.x ? x<p.x: y<p.y;
                                                	}
                                                	bool operator == (const pa3 &p) const{
                                                		return x==p.x && y==p.y && z==p.z;
                                                	}
                                                		bool operator != (const pa3 &p) const{
                                                			return !( x==p.x && y==p.y && z==p.z);
                                                	}
                                                
                                                };
                                                
                                                class pa4{
                                                	public:
                                                	int x;
                                                	int y,z,w;
                                                	pa4(int x=0,int y=0,int z=0,int w=0):x(x),y(y),z(z),w(w) {}
                                                	bool operator < (const pa4 &p) const{
                                                		if(x!=p.x) return x<p.x;
                                                		if(y!=p.y) return y<p.y;
                                                		if(z!=p.z)return z<p.z;
                                                		return w<p.w;
                                                		//return x != p.x ? x<p.x: y<p.y;
                                                	}
                                                	bool operator > (const pa4 &p) const{
                                                		if(x!=p.x) return x>p.x;
                                                		if(y!=p.y) return y>p.y;
                                                		if(z!=p.z)return z>p.z;
                                                		return w>p.w;
                                                		//return x != p.x ? x<p.x: y<p.y;
                                                	}
                                                	bool operator == (const pa4 &p) const{
                                                		return x==p.x && y==p.y && z==p.z &&w==p.w;
                                                	}
                                                	
                                                	bool operator != (const pa4 &p) const{
                                                		return !(x==p.x && y==p.y && z==p.z &&w==p.w);
                                                	}
                                                		
                                                
                                                };
                                                class pa2{
                                                	public:
                                                	int x,y;
                                                	pa2(int x=0,int y=0):x(x),y(y) {}
                                                	pa2 operator + (pa2 p) {return pa2(x+p.x,y+p.y);}
                                                	pa2 operator - (pa2 p) {return pa2(x-p.x,y-p.y);}
                                                	bool operator < (const pa2 &p) const{
                                                		return x!= p.x ? x<p.x: y<p.y;
                                                	}
                                                	bool operator > (const pa2 &p) const{
                                                		return x != p.x ? x>p.x: y>p.y;
                                                	}
                                                	bool operator == (const pa2 &p) const{
                                                		return abs(x-p.x)==0 && abs(y-p.y)==0;
                                                	}
                                                	bool operator != (const pa2 &p) const{
                                                		return !(abs(x-p.x)==0 && abs(y-p.y)==0);
                                                	}
                                                		
                                                
                                                };
                                                
                                              
                                                
                                                       #define ppa pair<int,pas>
                                                class Point{
                                                	public:
                                                	double x,y;
                                                	Point(double x=0,double y=0):x(x),y(y) {}
                                                	Point operator + (Point p) {return Point(x+p.x,y+p.y);}
                                                	Point operator - (Point p) {return Point(x-p.x,y-p.y);}
                                                	Point operator * (double a) {return Point(x*a,y*a);}
                                                	Point operator / (double a) {return Point(x/a,y/a);}
                                                	double absv() {return sqrt(norm());}
                                                	double norm() {return x*x+y*y;}
                                                	bool operator < (const Point &p) const{
                                                		return x != p.x ? x<p.x: y<p.y;
                                                	}
                                                	bool operator == (const Point &p) const{
                                                		return fabs(x-p.x)<EPS && fabs(y-p.y)<EPS;
                                                	}
                                                };
                                                typedef Point Vector;
                                         #define pl pair<int,pas>
                                                struct Segment{
                                                Point p1,p2;
                                                };
                                                 double dot(Vector a,Vector b){
                                                	return a.x*b.x+a.y*b.y;
                                                }
                                                double cross(Vector a,Vector b){
                                                	return a.x*b.y-a.y*b.x;
                                                }
                                            
                    bool parareru(Point a,Point b,Point c,Point d){
                    //	if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
                    	return abs(cross(a-b,d-c))<EPS;
                    }
                    double distance_ls_p(Point a, Point b, Point c) {
                      if ( dot(b-a, c-a) < EPS ) return (c-a).absv();
                      if ( dot(a-b, c-b) < EPS ) return (c-b).absv();
                      return abs(cross(b-a, c-a)) / (b-a).absv();
                    }
                    bool is_intersected_ls(Segment a,Segment b) {
                    	if(a.p1==b.p1||a.p2==b.p1||a.p1==b.p2||a.p2==b.p2) return false;
                    	if(parareru((a.p2),(a.p1),(a.p1),(b.p2))&&parareru((a.p2),(a.p1),(a.p1),(b.p1))){
                    //		cout<<"sss"<<endl;
                    		if(dot(a.p1-b.p1,a.p1-b.p2)<EPS) return true;
                    		if(dot(a.p2-b.p1,a.p2-b.p2)<EPS) return true;
                    		if(dot(a.p1-b.p1,a.p2-b.p1)<EPS) return true;
                    		if(dot(a.p1-b.p2,a.p2-b.p2)<EPS) return true;
                    		return false;
                    	}
                      else return ( cross(a.p2-a.p1, b.p1-a.p1) * cross(a.p2-a.p1, b.p2-a.p1) < EPS ) && ( cross(b.p2-b.p1, a.p1-b.p1) * cross(b.p2-b.p1, a.p2-b.p1) < EPS );
                    }
                     
                    double segment_dis(Segment a,Segment b){
                    	if(is_intersected_ls(a,b))return 0;
                    	double r=distance_ls_p(a.p1, a.p2, b.p1);
                    	r=min(r,distance_ls_p(a.p1, a.p2, b.p2));
                    	r=min(r,distance_ls_p(b.p1, b.p2, a.p2));
                    	r=min(r,distance_ls_p(b.p1, b.p2, a.p1));
                    	return r;
                    }
                    Point intersection_ls(Segment a, Segment b) {
                      Point ba = b.p2-b.p1;
                      double d1 = abs(cross(ba, a.p1-b.p1));
                      double d2 = abs(cross(ba, a.p2-b.p1));
                      double t = d1 / (d1 + d2);
                     
                      return a.p1 + (a.p2-a.p1) * t;
                    }
                     
                                    string itos( int i ) {
                                    ostringstream s ;
                                    s << i ;
                                    return s.str() ;
                                    }
                                     
                                    int gcd(int v,int b){
                                    	if(v>b) return gcd(b,v);
                                    	if(v==b) return b;
                                    	if(b%v==0) return v;
                                    	return gcd(v,b%v);
                                    }
                     
                                    double distans(double x1,double y1,double x2,double y2){
                                    	double rr=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
                                    	return sqrt(rr);
                                    	
                                    }
                                                        /*
        double bekid(double w,int r){
        	if(r==0) return 1.0;
        	if(r==1) return w;
        	if(r%2) return bekid(w,r-1)*w;
        	double f=bekid(w,r/2);
        	return f*f;
        }*/
                                    int mod;
                          /*          
                    int pr[401000];
                    int inv[401000];
                   
                    int beki(int wa,int rr,int warukazu){
                    	if(rr==0) return 1%warukazu;
                    	if(rr==1) return wa%warukazu;
                    	if(rr%2==1) return (beki(wa,rr-1,warukazu)*wa)%warukazu;
                    	int zx=beki(wa,rr/2,warukazu);
                    	return (zx*zx)%warukazu;
                    }

                  
        			int comb(int nn,int rr){
        				int r=pr[nn]*inv[rr];
        				r%=mod;
        				r*=inv[nn-rr];
        				r%=mod;
        				
        				return r;
        			}
                  
                    void gya(int ert){
                    	pr[0]=1;
                    	for(int i=1;i<ert;i++){
                    		pr[i]=(pr[i-1]*i)%mod;
                    	}
                    	for(int i=0;i<ert;i++) inv[i]=beki(pr[i],mod-2,mod);
                    	
                    }
                    */
                    
                  //   cin.tie(0);
        		//	ios::sync_with_stdio(false);
        			//priority_queue<pa3,vector<pa3>,greater<pa3>> pq;            
                     //sort(ve.begin(),ve.end(),greater<int>());
   
 
                                          //----------------kokomade tenpure------------

vector<int >G[5010],G2[5010];
void dfs1(int r,int p){
	for(auto v:G[r])if(v!=p){
		G2[r].pb(v);
		dfs1(v,r);
	}
}

vector<int> dp0[5010],dp1[5010];
#define VI vector<int>

int pre[10100];

pair<VI,VI> shoki(int r){
	int ma=dp0[r].size()-1;
	
	vector<int> ve0(ma+2,0),ve1(ma+2,0);
	
	for(int i=1;i<=ma;i++){
		ve0[i+1]+=dp0[r][i];
		ve1[i+1]+=dp1[r][i];
		ve1[i+1]%=inf;
		ve0[i+1]%=inf;
		if(ve1.size()<=i+1)exit(1);
		if(ve0.size()<=i+1)exit(1);
	}
	for(int i=1;i<=ma;i++){
		ve0[1]+=dp1[r][i]*pre[i];
		ve1[1]+=dp0[r][i]*pre[i];
		ve1[1]%=inf;
		ve0[1]%=inf;
	}
	return mp(ve0,ve1);
}


pair<VI,VI> marg(pair<VI,VI> moto,int r){
	int ma1=moto.first.size()-1;
	int ma2=dp0[r].size()-1;
	
	vector<int> ve0(ma1+ma2+1,0),ve1(ma2+ma1+1,0);
	
	for(int i=1;i<=ma1;i++)for(int j=1;j<=ma2;j++){
		ve0[i+j]+=moto.first[i]*dp0[r][j];
		ve0[i+j]%=inf;
		ve0[i+j]+=moto.second[i]*dp1[r][j];
		ve0[i+j]%=inf;
		
		ve1[i+j]+=moto.first[i]*dp1[r][j];
		ve1[i+j]%=inf;
		ve1[i+j]+=moto.second[i]*dp0[r][j];
		ve1[i+j]%=inf;
		
		ve1[i]+=moto.first[i]*((dp0[r][j]*pre[j])%inf);
		ve1[i]%=inf;
		ve1[i]+=moto.second[i]*((dp1[r][j]*pre[j])%inf);
		ve1[i]%=inf;
		
		ve0[i]+=moto.first[i]*((dp1[r][j]*pre[j])%inf);
		ve0[i]%=inf;
		ve0[i]+=moto.second[i]*((dp0[r][j]*pre[j])%inf);
		ve0[i]%=inf;
		
		if(ve1.size()<=i+j)exit(1);
		if(ve0.size()<=i+j)exit(1);
	}
	return mp(ve0,ve1);
}
void dfs(int r){
//	cout<<r<<endl;
	for(auto v:G2[r])dfs(v);
	if(G2[r].size()==0){
		dp0[r].pb(0);
		dp0[r].pb(1);
		dp1[r].pb(0);
		dp1[r].pb(0);
		return;
	}
	
	pair<VI,VI> pv=shoki(G2[r][0]);
	for(int i=1;i<G2[r].size();i++){
	
		pv=marg(pv,G2[r][i]);

	}
	
	dp0[r]=pv.first;
	dp1[r]=pv.second;
	/*
	cout<<r<<endl;
	for(auto v:dp0[r])cout<<v<<" ";
	cout<<endl;
	for(auto v:dp1[r])cout<<v<<" ";
	cout<<endl;
	cout<<endl;
	*/
	return;
}

  signed main(){
  	              cin.tie(0);
    		ios::sync_with_stdio(false);
mod=inf;
  	for(int i=1;i<=10000;i++){
  		if(i%2)pre[i]=0;
  		else if(i==2) pre[i]=1;
  		else {
  			pre[i]=pre[i-2]*(i-1);
  			pre[i]%=inf;
  		}
  	}
  	int n;
 // 	gya(10020);
  	cin>>n;
  	for(int i=0;i<n-1;i++){
  		int y,yy;
  		cin>>y>>yy;
  		G[y].pb(yy);
  		G[yy].pb(y);
  	}
  	dfs1(1,1);
  	dfs(1);
  	int s=dp0[1].size();
  	int ans=0;
  	for(int i=1;i<s;i++){
  		ans+=(dp0[1][i]*pre[i])%inf;
  		ans%=inf;
  		
  		ans+=inf-(dp1[1][i]*pre[i])%inf;
  		ans%=inf;
  	}
  	
  	cout<<ans<<endl;
  	return 0;
                }
                




Measured memory_bytes: 139136