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

#define INF 1e9

int main() {
    int n, m;
    cin >> n >> m;

    vector<int> a(n + 1);

    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }

    vector<vector<int>> adj(n + 1);

    for (int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;

        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    int k;
    cin >> k;

    // Add super-source 0
    vector<vector<int>> G(n + 1);

    for (int i = 1; i <= n; i++) {
        G[i] = adj[i];

        if (a[i] == 0) {
            G[0].push_back(i);
            G[i].push_back(0);
        }
    }

    // BFS from super-source
    queue<int> q;
    vector<int> dist(n + 1, INF);

    q.push(0);
    dist[0] = 0;

    while (!q.empty()) {
        int u = q.front();
        q.pop();

        for (int v : G[u]) {
            if (dist[v] == INF && dist[u] + 1 <= k + 1) {
                dist[v] = dist[u] + 1;
                q.push(v);
            }
        }
    }

    // Infect nodes within distance k of a virus
    for (int i = 1; i <= n; i++) {
        if (dist[i] <= k + 1) {
            a[i] = 0;
        }
    }

    // BFS from 1 to n
    queue<int> q2;
    vector<int> d(n + 1, INF);

    if (a[1] == 1) {
        q2.push(1);
        d[1] = 0;
    }

    while (!q2.empty()) {
        int u = q2.front();
        q2.pop();

        for (int v : adj[u]) {
            if (a[v] == 1 && d[v] == INF) {
                d[v] = d[u] + 1;
                q2.push(v);
            }
        }
    }

    cout << (d[n] == INF ? -1 : d[n]) << '\n';
}