///TRAN THAI BAO :3
#include <iostream>
#include <cstdio>
#include <vector>
#include <queue>
using namespace std;
#define maxN 200007
#define oo 1e18
typedef pair<long long, long long> pii;
int n, m;
long long a[maxN];
long long minD[maxN];
vector<int>adj[maxN];
priority_queue<pii, vector<pii>, greater<pii> >pq;
void readData()
{
cin >> n >> m;
for(int i = 1; i <= n; i++)
{
cin >> a[i];
minD[i] = oo;
}
minD[1] = 0;
int u, v;
for(int i = 0; i < m; i++)
{
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
}
void solve()
{
pq.push({minD[1], 1});
while(!pq.empty())
{
pii cur = pq.top();
pq.pop();
if(minD[cur.second] != cur.first)
continue;
int u, v;
long long w;
u = cur.second;
for(int i = 0; i < adj[u].size(); i++)
{
v = adj[u][i];
w = max(abs(a[u] - a[v]), 1ll);
if(minD[v] > minD[u] + w)
{
minD[v] = minD[u]+w;
pq.push({minD[v], v});
}
}
}
cout << minD[n];
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
readData();
solve();
return 0;
}
