#include<bits/stdc++.h>
using namespace std;

#define cout cerr
#define rep(i,a,b) for(int i=(a);i<=(b);++i)
#define per(i,a,b) for(int i=(a);i>=(b);--i)

typedef long long ll;
typedef pair<int,int> pii;
#define FR first
#define SE second

inline void rd(int &x){
	x=0;char ch=getchar();int f=1;
	while(ch<'0'||ch>'9'){
		if(ch=='-')f=-1;
		ch=getchar();
	}
	while(ch>='0'&&ch<='9'){
		x=x*10+ch-'0';
		ch=getchar();
	}
	x*=f;
}

int n,m,K;
#define Maxn 1005
#define E 2000010

void output(vector<int> sol){
	printf("%d\n",sol.size());
	for(int i=0;i<sol.size();++i)printf("%d\n",sol[i]);
	exit(0);
}

vector<int> vec[Maxn];
bool cir[Maxn];
int ALL;
void calc(){
	vector<int> sol;
	rep(u,1,n)
		if(vec[u].size()>0){
			sol.push_back(u);cir[u]=true;
			while(true){
				bool fl=false;
				for(int i=0;i<vec[u].size();++i)
					if(!cir[vec[u][i]]){
						u=vec[u][i];cir[u]=true;sol.push_back(u);
						fl=true;break;
					}
				if(!fl)break;
			}
			output(sol);
		}
}
void addcir(int s,int e){
	//cout<<"s e "<<s<<" "<<e<<endl;
	vec[s].push_back(e);
	vec[e].push_back(s);
	if(vec[s].size()==1)ALL--;else ALL++;
	if(vec[e].size()==1)ALL--;else ALL++;
	if(ALL==n)calc();
}

int rev(int x){
	if(x&1)return x+1;
	return x-1;
}
int p(int x){return (x+1)/2;}
vector<int> e[Maxn];int cnt=0;
namespace P1{
	int del[Maxn],ed[E],delt,edt;
	int head[Maxn],v[E],nxt[E],tot=0;
	pii edge[E];int len=0;
	void ADD(int s,int e){
		cout<<"s e "<<s<<" "<<e<<endl;
		edge[++len]=pii(s,e);
	}
	inline void add_edge(int s,int e){
		tot++;v[tot]=e;nxt[tot]=head[s];head[s]=tot;
		tot++;v[tot]=s;nxt[tot]=head[e];head[e]=tot;
	}
	
	int dfn[Maxn],dfk,low[Maxn];
	int fav[Maxn],d[Maxn];
	void tarjan(int u,int f){
		fav[u]=f;d[u]=0;
		dfn[u]=low[u]=++dfk;
		for(int i=head[u];i;i=nxt[i])
			if(rev(i)!=f&&!del[v[i]]&&!ed[p(i)]){
				if(!dfn[v[i]]){
					tarjan(v[i],i);
					low[u]=min(low[u],low[v[i]]);
				}else{
					low[u]=min(low[u],dfn[v[i]]);
					if(!d[u]||dfn[v[i]]<dfn[v[d[u]]])d[u]=i;
				}
			}
	}
	
	bool Judge(){
		rep(i,1,len)
			if(!del[edge[i].FR]&&!del[edge[i].SE]&&!ed[i])return true;
		return false;
	}
	
	void shrink(){
		while(true){
			dfk=0;
			memset(dfn,0,sizeof(int)*(n+1));
			rep(u,1,n)
				if(!del[u]&&!dfn[u])tarjan(u,0);
			bool fl=true;
			rep(u,1,n)
				if(!del[u]&&low[u]==dfn[u]){
					int t=p(fav[u]);
					if(t){
						if(t>len-cnt){del[edge[t].FR]=delt;del[edge[t].SE]=delt;fl=false;}
						ed[t]=edt;
					}
				}
			if(fl)break;
		}
	}
	void back(){
		rep(u,1,n)
			if(del[u]==delt)del[u]=0;
		rep(i,1,len)
			if(ed[i]==edt)ed[i]=0;
		
	}
	void solve(){
		delt=edt=1;
		rep(i,1,len)add_edge(edge[i].FR,edge[i].SE);
		shrink();
		dfk=0;memset(dfn,0,sizeof(int)*(n+1));
		rep(u,1,n)
			if(!del[u]&&!dfn[u])tarjan(u,0);
		rep(u,1,n)
			if(!del[u])ed[p(d[u])]=ed[p(fav[u])]=2;
		int pre=len;len=0;int zz=cnt;cnt=0;
		rep(i,1,pre)
			if(ed[i]==2){
				if(i>pre-zz){
					cnt++;e[cnt]=e[i-pre+zz];
					edge[++len]=edge[i];
				}else edge[++len]=edge[i];
			}
		rep(i,cnt+1,zz)e[i].clear();
		memset(ed,0,sizeof(int)*(len+1));
		memset(head,0,sizeof(int)*(n+1));tot=0;
		rep(i,1,len)add_edge(edge[i].FR,edge[i].SE);
		if(len==0){
			puts("-1");
			exit(0);
		}
		per(i,len,1)
			if(!del[edge[i].FR]&&!del[edge[i].SE]&&!ed[i]){
				delt++;edt++;
				if(i>len-cnt)del[edge[i].FR]=del[edge[i].SE]=delt;
				ed[i]=edt;
				shrink();
				if(!Judge()){
					back();
					if(i<=len-cnt)addcir(edge[i].FR,edge[i].SE);
					else{
						int z=i-len+cnt;
						for(int j=0;j+1<e[z].size();++j)addcir(e[z][j],e[z][j+1]);
					}
				}
			}
	}
}

namespace P2{
	int head[Maxn],v[E],nxt[E],tot=0;
	int deg[Maxn];
	void add_edge(int s,int e){
		deg[s]++;deg[e]++;
		tot++;v[tot]=e;nxt[tot]=head[s];head[s]=tot;
		tot++;v[tot]=s;nxt[tot]=head[e];head[e]=tot;
	}
	bool vis[Maxn];
	int mx,s;
	vector<int> node;
	void dfs(int u){
		node.push_back(u);
		mx=max(mx,deg[u]);s+=deg[u];vis[u]=true;
		for(int i=head[u];i;i=nxt[i])
			if(!vis[v[i]])
				dfs(v[i]);
	}
	void build(){
		rep(u,1,n)
			if(!vis[u]){
				mx=0;s=0;node.clear();
				dfs(u);s/=2;
				if(mx>2){
					for(int i=0;i<node.size();++i)P1::del[node[i]]=1;
				}else{
					if(s==node.size()-1){
						if(node.size()>1){
							for(int i=0;i<node.size();++i)
								if(deg[node[i]]==1){
									reverse(node.begin(),node.begin()+i+1);
									break;
								}
							cnt++;
							e[cnt]=node;
							for(int i=1;i+1<node.size();++i)P1::del[node[i]]=1;
							P1::ADD(node[0],node[node.size()-1]);
						}
					}else output(node);
				}
			}
	}
}

int main(){
	rd(n);rd(m);rd(K);ALL=n;
	rep(i,1,m){
		int s,e;rd(s);rd(e);
		if(i<=K)P2::add_edge(s,e);
		else P1::ADD(s,e);
	}
	P2::build();
	P1::solve();
	return 0;
}/*
8 10 3
1 2
4 5
7 8
2 3
3 4
1 4
5 6
6 7
5 8
3 8

4 6 3
1 2
1 3
1 4
2 3
3 4
2 4
*/