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

namespace FastIO
{

class FastIOBase
{
 protected:
#ifdef OPENIOBUF
	static const int BUFSIZE=1<<22;
	char buf[BUFSIZE+1];
	int buf_p=0;
#endif
	FILE *target;
 public:
#ifdef OPENIOBUF
	virtual void flush()=0;
#endif
	FastIOBase(FILE *f): target(f){}
	~FastIOBase()=default;
};

class FastOutput: public FastIOBase
{
#ifdef OPENIOBUF
 public:
	inline void flush()
		{ fwrite(buf,1,buf_p,target),buf_p=0; }
#endif
 protected:
	inline void __putc(char x)
	{
#ifdef OPENIOBUF
		if(buf[buf_p++]=x,buf_p==BUFSIZE)flush();
#else
		putc(x,target);
#endif
	}
	template<typename T>
	inline void __write(T x)
	{
		static char stk[64],*top;top=stk;
		if(x<0) return __putc('-'),__write(-x);
		do *(top++)=x%10,x/=10; while(x);
		for(;top!=stk;__putc(*(--top)+'0'));
	}
 public:
	FastOutput(FILE *f=stdout): FastIOBase(f){}
#ifdef OPENIOBUF
	inline void setTarget(FILE *f) { this->flush(),target=f; }
	~FastOutput(){ flush(); }
#else
	inline void setTarget(FILE *f) { target=f; }
#endif
	template<typename ...T>
	inline void writesp(const T &...x)
		{ initializer_list<int>{(this->operator<<(x),__putc(' '),0)...}; }
	template<typename ...T>
	inline void writeln(const T &...x)
		{ initializer_list<int>{(this->operator<<(x),__putc('\n'),0)...}; }
	inline FastOutput &operator <<(char x)
		{ return __putc(x),*this; }
	inline FastOutput &operator <<(const char *s)
		{ for(;*s;__putc(*(s++)));return *this; }
	inline FastOutput &operator <<(const string &s)
		{ return (*this)<<s.c_str(); }
	template<typename T,typename=typename enable_if<is_integral<T>::value>::type>
	inline FastOutput &operator <<(const T &x)
		{ return __write(x),*this; }
}qout;

class FastInput: public FastIOBase
{
#ifdef OPENIOBUF
 public:
	inline void flush()
		{ buf[fread(buf,1,BUFSIZE,target)]='\0',buf_p=0; }
#endif
 protected:
	inline char __getc()
	{
#ifdef OPENIOBUF
		if(buf_p==BUFSIZE) flush();
		return buf[buf_p++];
#else
		return getc(target);
#endif
	}
 public:
#ifdef OPENIOBUF
	FastInput(FILE *f=stdin): FastIOBase(f){ buf_p=BUFSIZE; }
	inline void setTarget(FILE *f) { this->flush(),target=f; }
#else
	FastInput(FILE *f=stdin): FastIOBase(f){}
	inline void setTarget(FILE *f) { target=f; }
#endif
	inline char getchar() { return __getc(); }
	template<typename ...T>
	inline void read(T &...x)
		{ initializer_list<int>{(this->operator>>(x),0)...}; }
	inline FastInput &operator >>(char &x)
		{ while(isspace(x=__getc()));return *this; }
	template<typename T,typename=typename enable_if<is_integral<T>::value>::type>
	inline FastInput &operator >>(T &x)
	{
		static char ch,sym;x=sym=0;
		while(isspace(ch=__getc()));
		if(ch=='-') sym=1,ch=__getc();
		for(;isdigit(ch);x=(x<<1)+(x<<3)+(ch^48),ch=__getc());
		return sym?x=-x:x,*this;
	}
	inline FastInput &operator >>(char *s)
	{
		while(isspace(*s=__getc()));
		for(;!isspace(*s) && *s && ~*s;*(++s)=__getc());
		return *s='\0',*this;
	}
	inline FastInput &operator >>(string &s)
	{
		char str_buf[(1<<8)+1],*p=str_buf;
		char *const buf_end=str_buf+(1<<8);
		while(isspace(*p=__getc()));
		for(s.clear(),p++;;p=str_buf)
		{
			for(;p!=buf_end && !isspace(*p=__getc()) && *p && ~*p;p++);
			*p='\0',s.append(str_buf);
			if(p!=buf_end) break;
		}
		return *this;
	}
}qin;

} // namespace FastIO
using namespace FastIO;

using LL=long long;
using LD=long double;
using UI=unsigned int;
using ULL=unsigned long long;
constexpr LL INF=1e16;

#ifndef DADALZY
#define FILEIO(file) freopen(file".in","r",stdin),freopen(file".out","w",stdout)
#else
#define FILEIO(file)
#endif

namespace NetworkFlow
{
	
template<int MAXN,int MAXM,typename FlowT=int,
		 typename=typename enable_if<is_integral<FlowT>::value>::type>
class MFGraph
{
 public:
	struct Edge{ int to,nxt;FlowT w; }e[2*MAXM+5];
	int head[MAXN+5];
 private:
	int cnt,headd[MAXN+5],dep[MAXN+5];
	inline void __addEdge(int u,int v,FlowT w)
		{ e[++cnt]=(Edge){v,head[u],w},head[u]=cnt; }
	bool bfs(int S,int T)
	{
		static int hd,tl,q[MAXN+5];
		memset(dep,0,sizeof(dep));
		memcpy(headd,head,sizeof(head));
		q[hd=tl=1]=S,dep[S]=1;
		for(int u=q[hd];(hd++)<=tl;u=q[hd])
			for(int i=head[u],v;v=e[i].to,i;i=e[i].nxt)
				if(e[i].w && !dep[v])
					dep[v]=dep[u]+1,q[++tl]=v;
		return dep[T];
	}
	FlowT dfs(int u,int T,FlowT flow=numeric_limits<FlowT>::max())
	{
		if(u==T || !flow) return flow;
		FlowT res=flow;
		for(int &i=headd[u],v;v=e[i].to,i;i=e[i].nxt)
			if(e[i].w && dep[v]==dep[u]+1)
			{
				FlowT c=dfs(v,T,min(res,e[i].w));
				e[i].w-=c,e[i^1].w+=c;
				if(!(res-=c)) break;
			}
		if(res==flow) dep[u]=0;
		return flow-res;
	}
 public:
	MFGraph(){ clear(); }
	inline void clear()
		{ cnt=1,memset(head,0,sizeof(head)); }
	inline void addEdge(int u,int v,FlowT w)
		{ __addEdge(u,v,w),__addEdge(v,u,0); }
	inline FlowT maxFlow(int S,int T)
	{
		FlowT res=0;
		while(bfs(S,T)) res+=dfs(S,T);
		return res;
	}
};

} // namespace NetworkFlow
using namespace NetworkFlow;

int n,m,k,S,T,a[205],nn,pi[205][10],po[205][10];
bool vis[205];
MFGraph<10000,1000000,LL> g;
void dfs(int u)
{
	if(vis[u]) return;
	vis[u]=true;
	for(int i=g.head[u];i;i=g.e[i].nxt)
		if(g.e[i].w) dfs(g.e[i].to);
}
int main()
{
	qin>>n>>m>>k;
	qin>>S>>T;
	for(int i=1;i<=n;i++)
	{
		qin>>a[i];
		for(int j=0;j<k;j++) pi[i][j]=++nn,po[i][j]=++nn;
		for(int j=1;j<k;j++) g.addEdge(pi[i][j-1],pi[i][j],INF);
		for(int j=1;j<k;j++) g.addEdge(pi[i][j-1],po[i][j],INF);
		for(int j=0;j<k;j++) g.addEdge(pi[i][j],po[i][j],a[i]);
	}
	for(int i=1,u,v;i<=m;i++)
	{
		qin>>u>>v;
		for(int j=0;j<k;j++) g.addEdge(po[u][j],pi[v][j],INF);
	}
	LL res=g.maxFlow(pi[S][0],po[T][k-1]);
	if(res>=INF) return qout<<-1,0;
	dfs(pi[S][0]);
	vector<int> ans;
	for(int i=1;i<=n;i++)
	{
		bool fl=false;
		for(int j=0;j<k;j++)
			if(vis[pi[i][j]]>vis[po[i][j]]) fl=true;
		if(fl) ans.push_back(i);
	}
	qout.writeln(ans.size());
	for(auto &i: ans) qout<<i<<' ';
	return 0;
}