#include <iostream>
#include <algorithm> // for sort, mainly
#include <vector>
#include <map>
#include <set>
#include <cmath>
#include <array>
#include <string>
#include <cstdio>
#include <iterator>
#include <unordered_set>
#include <cstdint> // for int64_t, int32_t, etc
#include <queue>
#include <stack>
#include <deque>
#include <numeric> // gcd, lcm
#include <fstream>
#include <bitset> // for bitset
#include <iomanip>
#include <cassert> // for set with custom ordering
#include <type_traits> // for set with custom ordering
#include <utility> // for swap, forward, etc
using namespace std;

#pragma GCC optimize("O2")
// #pragma GCC optimize("O1","O2","O3","Ofast","unroll-loops")
//#pragma GCC target("sse","sse2","sse3","sse4.1","sse4.2","avx","avx2","fma")

template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
void dbg_out() { cout << endl; }
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cout << ' ' << H; dbg_out(T...); }
#ifdef LOCAL
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif

/*
 *
 * notes:
 *
 * int64_t
 * stoi(string s) -> string to int
 * to_string() -> int (or else) to string
 *
 * vector declaration:
 * vector<ll> v(n, 0)
 * vector<vector<ll>> v(n, vector<ll>(n, 0));
 *
 * {if statement} ? {truth value} : {false value}
 *
 * set lower bound/upper bound:
 * 	// . . . m1 . . . d . . . . m2
 *    auto m1_it = b.lower_bound(d);
 *    advance(m1_it, -1);
 *    m1 = *m1_it;
 *	m2 = *b.upper_bound(d);
 *
 * #ifdef LOCAL
 *    freopen("in.txt","r",stdin);
 *    freopen("out.txt","w",stdout);
 * #endif
 *
 * constexpr auto lcm(auto x, auto... xs)
 * {
 *	return ((x = std::lcm(x, xs)), ...);
 * }
 *
 * std::gcd(int a, int b)
 *
 * cout << setprecision(n);
 *
 * set with custom ordering
 * set<ll, decltype(&cmp)> qu(cmp);
 *
 */

typedef int64_t ll;

void solve() {

    ll n, m;
    cin >> n >> m;
    vector<ll> dp(n+1, 0);
    vector<ll> v(n+1, 0);
    vector<vector<ll>> out(n+1);
    vector<vector<ll>> in(n+1);
    vector<ll> ind(n+1, 0); // indegree

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

    for(ll i = 0; i < m; i++) {
        ll from, to;
        cin >> from >> to;  
        out[from].push_back(to);
        ind[to]++;
        in[to].push_back(from);
    }

    queue<ll> q;
    // check if connected
    q.push(1);
    bool nvis = false;
    vector<bool> vis(n+1, false);
    while(!q.empty()) {

        ll curr = q.front();
        q.pop();

        if(curr == n) {
            nvis = true;
        }

        for(const auto & x : out[curr]) {
            if(vis[x] == false) {
                vis[x] = true;
                q.push(x);
            }
        }

    }

    if(nvis == false){
        cout << "-1";
        return;
    }
    
    
    vector<ll> ts(n, 0);
    ll tind = 0;

    for(ll i = 1; i <= n; i++) {
        if(ind[i] == 0) {
            q.push(i);
        }
    }
    
    while(!q.empty()) {
        ll curr = q.front();
        q.pop();

        ts[tind] = curr;
        tind++;

        for(const auto & x : out[curr]) {
            ind[x]--;
            if(ind[x] == 0) {
                q.push(x);
            }
        }
    }

    //cerr << "\nts=" << ts;

    vector<ll> p(n+1, -1);

    ll mxdp = 0;
    ll mxnode = -1;

    dp[1] = v[1];

    for(const auto & node : ts) {

        ll mx = 0;
        ll parent = -1;
        for(const auto & here : in[node]) {
            if(dp[here] > mx) {
                mx = dp[here];
                parent = here;
            }
        }


        p[node] = parent;
        if(mx > 0) {
            dp[node] = mx + v[node];
        }
        
        if(dp[node] > mxdp) {
            mxdp = dp[node];
            mxnode = node;
        }
    }

    //cerr << "\ndp=" << dp;

    vector<ll> res;
    ll curr = n;
    while(curr != -1) {
        res.push_back(curr);
        curr = p[curr];
    }

    reverse(res.begin(), res.end());
    cout << mxdp << "\n";
    for(const auto & x : res) {
        cout << x << " ";
    }



}

int main()
{
    std::ios_base::sync_with_stdio(false);
    //cin.tie(nullptr);
    //cout.tie(nullptr);

    solve();

    return 0;
}