#include <bits/stdc++.h> 

using namespace std;
typedef long long ll;

const int R = 205, K = 6, N = 10005;
const ll inf = 1e10 + 5;
int n, m, k, cnt, tot = 1, S, E, s, t;
int in[R][K], out[R][K], d[N], v[N];
int fir[N], ver[N], nxt[N];
ll edge[N], flow, mincut;
bool bfs() {
	queue<int> q;
	for (int i = 1; i <= cnt; i++) d[i] = 0;
	d[s] = 1, q.push(s);
	while (q.size()) {
		int x = q.front(); q.pop();
		for (int i = fir[x], y; i; i = nxt[i]) {
			if (!d[y = ver[i]] && edge[i]) {
				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], y; i && rst; i = nxt[i]) {
		if (d[y = ver[i]] == d[x] + 1 && edge[i]) {
			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;
}
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;
}
int main() {
	scanf("%d%d%d%d%d", &n, &m, &k, &S, &E);
	for (int c, i = 1; i <= n; i++) {
		scanf("%d", &c);
		for (int j = 0; j < k; j++) {
			in[i][j] = ++cnt, out[i][j] = ++cnt;
			add(in[i][j], out[i][j], c);
		}
	}
	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);
	}
	s = in[S][0], t = ++cnt;
	for (int j = 0; j < k; j++) add(out[E][j], t, inf);
	
	while (bfs()) while ((flow = dinic(s, inf))) mincut += flow;
	
	if (mincut >= inf) printf("-1");
	vector<int> ans;
	for (int i = 1; i <= n; i++) {
		for (int j = 0; j < k; j++) 
			if (d[in[i][j]] && !d[out[i][j]]) { ans.push_back(i); break; }
	}
	printf("%d\n", ans.size());
	for (int x: ans) printf("%d ", x);
	return 0;
}