#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define vi vector<long long>
#define all(x) x.begin(), x.end()
#define endl "\n"
#define pr pair<ll, ll>
#define ff first
#define ss second
void solution();
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
solution();
return 0;
}
#define arr array<ll, 4>
const int N = 2e5+10;
vi adj[N];
ll a[N];
void solution() {
ll n, m; cin >> n >> m;
for (int i = 1; i <= n; i++) cin >> a[i];
while (m--) {
int u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
vi dist(n+1, 1e18);
dist[1] = 0;
priority_queue<arr> q;
q.push({0, 0, 1, 1});
vi cnt(n+1);
while (!q.empty()) {
auto [t, h, u, p] = q.top(); q.pop();
dist[u] = min(dist[u], -t);
if (cnt[u] >= 1000) continue;
cnt[u]++;
for (auto v : adj[u]) {
if (v == p) continue;
arr nxt;
nxt[0] = t-1;
nxt[1] = h;
nxt[2] = v;
nxt[3] = u;
if (h < a[v] || v == n) {
ll delta = abs(a[v]-h);
nxt[0] -= delta-1;
nxt[1] += delta;
}
q.push(nxt);
}
}
cout << dist[n] << endl;
}
