#include <cstdio>
#include <cmath>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <queue>
#include <vector>
#include <map>
#include <unordered_map>
#define ll long long
#define reg register
#define fo(a,b,c) for(reg ll a=b;a<=c;a++)
#define re(a,b,c) for(reg ll a=b;a>=c;a--)
#define pii pair<ll,ll>
#define fi first
#define pb push_back
#define se second
#define mod 1000000009
#define inf 9999999999999
using namespace std;
inline ll gi()
{
	ll x = 0, f = 1;
	char ch = getchar();
	while(ch < '0' || ch > '9')
	{
		if (ch == '-')
			f = -1;
		ch = getchar();
	}
	while(ch >= '0' && ch <= '9')
	{
		x = (x<<1) + (x<<3) + (ch^48);
		ch = getchar();
	}
	return x * f;
}
const int N=500005;
ll s,t;
ll cnt,head[30005],dep[30005],cur[30005];
struct IO
{
	ll u,v,w;
}node[N];
queue<ll> q;
ll bfs()
{
	memset(dep,0,sizeof(dep));
	q.push(s);
	dep[s]=1;
	while(!q.empty())
	{
		ll u=q.front();
		q.pop();
		for(ll i=head[u];i;i=node[i].u)
		{
			ll v=node[i].v;
			if(!dep[v]&&node[i].w)
			{
				dep[v]=dep[u]+1;
				q.push(v);
			}
		}
	}
	return dep[t]!=0;
}
ll dfs(ll u,ll f)
{
	if(u==t)
	{
		return f;
	}
	ll ttt=f;
	for(ll i=cur[u];i;i=node[i].u)
	{
		cur[u]=i;
		ll v=node[i].v;
		if(dep[v]==dep[u]+1&&node[i].w>0)
		{
			ll tmp=dfs(v,min(ttt,node[i].w));
			node[i].w-=tmp;
			node[i^1].w+=tmp;
			ttt-=tmp;
			if(!ttt) break;
		}
		if(!ttt) break;
	}
	return f-ttt;
}
ll n,m,k;
ll FLOW()
{
	ll ans=0;
	while(bfs())
	{	
		fo(i,1,(n*2+1)*k*2) cur[i]=head[i];
		ans+=dfs(s,inf);
	}
	if(ans>=inf) ans=-1;
	return ans;
}
void add(ll u,ll v,ll w)
{
	cnt++;
	node[cnt].u=head[u];
	head[u]=cnt;
	node[cnt].v=v;
	node[cnt].w=w;
	cnt++;
	node[cnt].u=head[v];
	head[v]=cnt;
	node[cnt].v=u;
	node[cnt].w=0;
}
ll c[N],tag[N];
int main()
{
	n=gi(),m=gi(),k=gi();
	s=gi(),t=gi();
	cnt=1;
	ll flo=2*n+1;
	fo(i,1,n)
	{
		c[i]=gi();
		fo(j,0,k-1)
		{
			add(j*flo+i*2,j*flo+i*2+1,c[i]);
			fo(zz,j+1,k-1)
			{
				add(j*flo+i*2,zz*flo+i*2+1,inf);
			}
		}
	}
	fo(i,1,m)
	{
		ll x=gi(),y=gi();
		fo(j,0,k-1)
		{
			add(j*flo+x*2+1,j*flo+y*2,inf);
		}
	}
	s=2*s;
	t=(k-1)*flo+t*2+1;
	ll z=FLOW();
	if(z>inf)
	{
		cout<<-1;
		return 0;
	}
	bfs();
	vector<ll> ot;
	fo(i,1,n)
	{
		fo(j,0,k-1)
		{
			if(dep[j*flo+i*2+1]==0&&dep[j*flo+i*2])
			{
				tag[i]=1;
			}
		}
	}
	fo(i,1,n) if(tag[i]) ot.pb(i);
	cout<<ot.size()<<'\n';
	for(ll x:ot)
	{
		cout<<x<<" ";
	}
	return 0;
}