#include <bits/stdc++.h> 


using namespace std;
typedef long long ll;

const int R = 205, K = 6, N = 1000005, M = 2000005;
const ll inf = 1e10 + 5;
int n, m, k, cnt, tot = 1, st, ed, s, t, num;
int in[R][K], out[R][K];
int fir[N], ver[M], nxt[M], d[N], v[N], ans[R];
ll edge[M], c[R], flow, mincut;

void add(int x, int y, ll z) {
	ver[++tot] = y, edge[tot] = z, nxt[tot] = fir[x], fir[x] = tot, 
	ver[++tot] = x, edge[tot] = 0, nxt[tot] = fir[y], fir[y] = tot;
}
bool bfs() {
	queue<int> q;
	for (int i = 1; i <= cnt; i++) d[i] = 0;
	while (q.size()) q.pop();
	q.push(s), d[s] = 1;
	while (!q.empty()) {
		int x = q.front(); q.pop();
		for (int i = fir[x]; i; i = nxt[i]) {
			int y = ver[i];
			if (d[y] || !edge[i]) continue;
			d[y] = d[x] + 1;
			q.push(y);
			if (y == t) return true;
		}
	}
	return false;
}
ll dinic(int x, ll flow) {
	if (x == t) return flow;
	ll rst = flow;
	for (int i = fir[x]; i && rst; i = nxt[i]) {
		int y = ver[i];
		if (edge[i] && d[y] == d[x] + 1) {
			ll k = dinic(y, min(rst, edge[i]));
			if (!k) d[y] = 0;
			edge[i] -= k;
			edge[i ^ 1] += k;
			rst -= k;
		}
	}
	return flow - rst;
}
int main() {
	//~ scanf("%d%d%d%d%d", &n, &m, &k, &st, &ed);
	//~ for (int i = 1; i <= n; i++) {
		//~ for (int j = 0; j < k; j++) 
			//~ in[i][j] = ++cnt, out[i][j] = ++cnt;
	//~ }
	//~ s = ++cnt, t = ++cnt; add(s, in[st][0], inf);
	//~ for (int j = 0; j < k; j++) add(out[ed][j], t, inf);
	//~ for (int i = 1; i <= n; i++) {
		//~ scanf("%d", &c[i]);
		//~ for (int j = 0; j < k; j++) 
			//~ add(in[i][j], out[i][j], c[i]);
	//~ }
	//~ for (int i = 1; i <= n; i++) {
		//~ for (int j = 0; j < k - 1; j++) 
			//~ add(in[i][j], out[i][j + 1], inf);
	//~ }
	//~ for (int x, y, i = 1; i <= m; i++) {
		//~ scanf("%d%d", &x, &y);
		//~ for (int j = 0; j < k; j++) 
			//~ add(out[x][j], in[y][j], inf);
	//~ }
	
	
	scanf("%d%d%d%d%d",&n,&m,&k,&st,&ed);
	for(ll i=1;i<=n;i++){
		for(ll j=0;j<k;j++){
			in[i][j]=++cnt;
			out[i][j]=++cnt;
		}
	}
	s=++cnt,t=++cnt;
	add(s,in[st][0],inf); 
	for(ll i=0;i<k;i++){
		add(out[ed][i],t,inf);
	}
	for(ll i=1;i<=n;i++){
		scanf("%lld",&c[i]);
		for(ll j=0;j<k;j++)add(in[i][j],out[i][j],c[i]);
		for(ll j=0;j<k-1;j++)add(in[i][j],out[i][j+1],inf);
		//如果说这条边c_i跑满了，就表明放了一个点，状态转移 
	}
	for(ll i=1;i<=m;i++){
		ll x,y;
		scanf("%lld%lld",&x,&y);
		for(ll j=0;j<k;j++){
			add(out[x][j],in[y][j],inf);
		}
	}
	
	while (bfs()) while ((flow = dinic(s, inf))) mincut += flow;
	//~ printf("mincut = %lld\n", mincut);
	if (mincut >= inf) return printf("-1"), 0;
	for (int i = 1; i <= n; i++) {
		for (int j = 0; j < k; j++) {
			if (d[in[i][j]] > d[out[i][j]]) { ans[++num] = i; break; }
		}
	}
	printf("%d\n", num);
	for (int i = 1; i <= num; i++) printf("%d ", ans[i]);
	return 0;
}