/*
膜拜传奇特级宗师 Afterglow 大神儿
今天在 florr 首页称您为大夏尊贵的大名儿
一股敬佩之情油生然而
您在 florr 为国争光，扬我大夏威名
向您献上最真挚的膜拜！！！
膜拜传奇特级宗师 Afterglow 大神儿，今，一，您，扬。向！
膜拜传奇特级宗师 Afterglow 大神儿，今，一，您，扬。向！
膜拜传奇特级宗师 Afterglow 大神儿，今，一，您，扬。向！
*/
/*
          _____                    _____                     _____                    _____
         /\    \                  /\    \                   /\    \                  /\    \
        /  \    \                /  \    \                 /  \____\                /  \    \
        \   \    \              /    \    \               /   /    /                \   \    \
         \   \    \            /      \    \             /   /    /                  \   \    \
          \   \    \          /   /\   \    \           /   /____/                    \   \    \
           \   \    \        /   /  \   \    \         /    |    |                     \   \    \
            \   \    \      /   /    \   \    \       /     |    |                      \   \    \
             \   \    \    /   /    / \   \    \     /      |    |                       \   \    \
              \   \    \  /   /    /   \   \    \   /       |____|__ _____                \   \    \
_______________\   \____\/   /____/     \   \    \ /   /|            \    \ _______________\   \____\
\                  /    /\   \    \      \   \    \\  / |    _________\____\\                  /    /
 \    ____________/____/  \   \    \      \   \____\\/__|   |    |           \    ____________/____/
  \   \    \               \   \    \     |   |    |    |   |    |            \   \    \
   \   \    \               \   \    \    |   |    |    |   |    |             \   \    \
    \   \    \               \   \    \   |   |____|    |   |    |              \   \    \
     \   \    \               \   \    \  /   /    /    \   |    |               \   \    \
      \   \    \               \   \    \/   /    /      \  |    |                \   \    \
       \   \____\               \   \___/   /    /        \ |    |                 \   \____\
        \  /    /                \         /    /          \|    |                  \  /    /
         \/____/                  \_______/____/            \____|                   \/____/
*/
#define poj
#define zcz
#ifdef poj
//C++
#include<iomanip>
#include<iostream>
//C
#include<cassert>
#include<cmath>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<ctime>
//STL
#include<algorithm>
#include<bitset>
#include<functional>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<string>
#include<vector>
//C++11
#if __cplusplus>=201103L
#include<chrono>
#include<random>
#include<unordered_set>
#include<unordered_map>
#endif
#else
#include<bits/stdc++.h>
#endif
using namespace std;
#ifdef zcz
class fastin{
	private:
#ifdef poj
	static const int MAXBF=1<<20;
#else
	const int MAXBF=1<<27;
#endif
	FILE *inf;
	char *inbuf,*inst,*ined;
	inline char _getchar(){
		if(inst==ined)inst=inbuf,ined=inbuf+fread(inbuf,1,MAXBF,inf);
		return inst==ined?EOF:*inst++;
	}
	public:
	fastin(FILE*_inf=stdin){
		inbuf=new char[MAXBF],inf=_inf,inst=inbuf,ined=inbuf;
	}
	~fastin(){delete inbuf;}
	template<typename Int> fastin&operator>>(Int &n){
		static char c;
		Int t=1;
		while((c=_getchar())<'0'||c>'9')if(c=='-')t=-1;
		n=(c^48);
		while((c=_getchar())>='0'&&c<='9')n=n*10+(c^48);
		n*=t;
		return *this;
	}
	fastin&operator>>(char&c){
		while((c=_getchar())<'!'||c>'~');
		return *this;
	}
	fastin&operator>>(char*s){
		int t=0;
		static char c;
		while((c=_getchar())==' '||c=='\n');
		s[t++]=c;
		while((c=_getchar())>='!'&&c<='~')s[t++]=c;
		s[t]='\0';
		return *this;
	}
}fi;
class fastout{
	private:
#ifdef poj
	static const int MAXBF=1<<20;
#else
	const int MAXBF=1<<27;
#endif
	FILE *ouf;
	char *oubuf,*oust,*oued;
	inline void _flush(){fwrite(oubuf,1,oued-oust,ouf);oued=oust;}
	inline void _putchar(char c){
		if(oued==oust+MAXBF)_flush(),oued=oubuf;
		*oued++=c;
		#ifdef local
		_flush();
		#endif
	}
	public:
	fastout(FILE*_ouf=stdout){
		oubuf=new char[MAXBF],ouf=_ouf,oust=oubuf,oued=oubuf;
	}
	~fastout(){_flush();delete oubuf;}
	template<typename Int> fastout&operator<<(Int n){
		if(n<0)_putchar('-'),n=-n;
		static char S[20];
		int t=0;
		do{S[t++]='0'+n%10,n/=10;}while(n);
		for(int i=0;i<t;++i)_putchar(S[t-i-1]);
		return *this;
	}
	fastout&operator<<(char c){_putchar(c);return *this;}
	fastout&operator<<(char*s){
		for(int i=0;s[i];++i)_putchar(s[i]);
		return *this;
	}
	fastout&operator<<(const char*s){
		for(int i=0;s[i];++i)_putchar(s[i]);
		return *this;
	}
}fo;
#define cin fi
#define cout fo
#else
#define czc ios::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#endif
#define mod7 1000000007
#define mod9 998244353
#define ll long long
#define isinf 0x3f3f3f3f
#define ilinf 0x7fffffff
#define lsinf 0x3f3f3f3f3f3f3f3f
#define llinf 0x7fffffffffffffff
#define pii pair<int,int>
#define fr first
#define sc second
#define next ___
#define pb push_back
#define N 4010
#define M 5000010
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b,c) for(int i=(a);i<=(b);i+=c)
#define Per(i,a,b,c) for(int i=(a);i>=(b);i-=c)
#define Gra(i) for(int i=h[x];i;i=next[i])
typedef int arr[N];
typedef int arm[M];
typedef ll arl[N];
typedef ll alm[M];
typedef double ard[N];
typedef double adm[M];
namespace modint{
	template<typename Int,Int mod>
	struct modint{
		Int v;
		modint(){v=0;}
		modint(Int a){v=a;}
		bool operator==(modint a){return v==a.v;}
		bool operator!=(modint a){return v!=a.v;}
		bool operator<(modint a){return v<a.v;}
		bool operator>(modint a){return v>a.v;}
		bool operator<=(modint a){return v<=a.v;}
		bool operator>=(modint a){return v>=a.v;}
		bool operator==(Int a){return v==a;}
		bool operator!=(Int a){return v!=a;}
		bool operator<(Int a){return v<a;}
		bool operator>(Int a){return v>a;}
		bool operator<=(Int a){return v<=a;}
		bool operator>=(Int a){return v>=a;}
		modint operator+(modint a){return v>mod-a.v?v-mod+a.v:v+a.v;}
		modint operator-(modint a){return v>a.v?v-a.v:v+mod-a.v;}
		modint operator*(modint a){return v*a.v%mod;}
		modint operator+=(modint a){*this=*this+a;return *this;}
		modint operator-=(modint a){*this=*this-a;return *this;}
		modint operator*=(modint a){*this=*this*a;return *this;}
		modint qpow(modint a,Int b){
			modint r(1);
			for(;b;b>>=1,a*=a)if(b&1)r*=a;
			return r;
		}
		modint operator/(modint a){return qpow(a,mod-2)*v;}
		modint operator/=(modint a){*this=*this/a;return *this;}
		modint&operator++(){*this=*this+1;return *this;}
		modint&operator--(){*this=*this-1;return *this;}
		const modint operator++(int){modint r=*this;++*this;return r;}
		const modint operator--(int){modint r=*this;--*this;return r;}
		#ifdef cout
		friend fastout&operator<<(fastout&out,modint n){out<<n.v;return out;}
		#else
		friend ostream&operator<<(ostream&out,modint n){out<<n.v;return out;}
		#endif
	};
	typedef modint<long long,1000000007> int7;
	typedef modint<long long,998244353> int9;
}
using namespace modint;
int n,m,k,S,T,tot=1,s,t,tp;
arr next,to,h,w,dep,cur,in[6],out[6],p;
void add(int x,int y,int z){
//	cout<<x<<' '<<y<<' '<<z<<'\n';
	to[++tot]=y;
	next[tot]=h[x];
	h[x]=tot;
	w[tot]=z;
	to[++tot]=x;
	next[tot]=h[y];
	h[y]=tot;
	w[tot]=0;
}
int bfs(){
	fill(dep+1,dep+1+t,0);
	For(i,1,t)cur[i]=h[i];
	dep[s]=1;
	queue<int>q;
	q.push(s);
	while(q.size()){
		int x=q.front();
		q.pop();
		Gra(i){
			int y=to[i],z=w[i];
			if(!dep[y]&&z){
				dep[y]=dep[x]+1;
				if(y==t)return 1;
				q.push(y);
			}
		}
	}
	return 0;
}
int dfs(int x,int v){
//	cout<<x<<' '<<v<<'\n';
	if(!v||x==t)return v;
	int tem=v;
	for(int i=cur[x];i;i=next[i]){
		cur[x]=i;
		int y=to[i],z=w[i];
		if(dep[y]!=dep[x]+1)continue;
		int vt=dfs(y,min(z,tem));
		if(!vt)continue;
		w[i]-=vt;
		w[i^1]+=vt;
		tem-=vt;
		if(!tem)break;
	}
	if(tem==v)dep[x]=0;
	return v-tem;
}
void solve(){
	cin>>n>>m>>k>>S>>T;
	For(i,1,n){
		int x;
		cin>>x;
		For(j,0,k-1){
			in[j][i]=++s;
			out[j][i]=++s;
			add(s-1,s,x);
			if(j){
				add(in[j-1][i],s,isinf);
			}
		}
	}
	For(i,1,m){
		int x,y;
		cin>>x>>y;
		For(j,0,k-1){
			add(out[j][x],in[j][y],isinf);
		}
	}
	++s;
	t=s+1;
	add(s,in[0][S],isinf);
	For(i,0,k-1){
		add(in[i][T],t,isinf);
	}
	int ans=0;
	while(bfs())ans+=dfs(s,isinf);
//	cout<<ans<<'\n';
	if(ans>=isinf){
		cout<<"-1\n";
		return;
	}
	For(i,1,n){
		For(j,0,k-1){
			if(dep[in[j][i]]&&!dep[out[j][i]]){
				p[++tp]=i;
				break;
			}
		}
	}
	cout<<tp<<'\n';
	For(i,1,tp){
		cout<<p[i]<<' ';
	}
	return;
}
int main(){
	#ifndef zcz
	czc;
	#endif
	timespec time1,time2;
	clock_gettime(CLOCK_REALTIME,&time1);
	int t=1;
	while(t--)solve();
	clock_gettime(CLOCK_REALTIME,&time2);
	while(1000000000ll*(time2.tv_sec-time1.tv_sec)+1ll*(time2.tv_nsec-time1.tv_nsec)<=996000000ll)clock_gettime(CLOCK_REALTIME,&time2);
	return 0;
}