#include <bits/stdc++.h>
using namespace std;
#define endl "\n"
#define int long long
#define pii pair<int, int>
#define ff first
#define ss second
#define entire(x) (x).begin(), (x).end()
const int inf = 9e18;
int32_t main(){
ios::sync_with_stdio(false); cin.tie(nullptr);
int n, m; cin >> n >> m;
vector<int> a(n);
for (int i = 0; i < n; i++) cin >> a[i];
vector<vector<int>> adj(n);
for (int i = 0; i < m; i++){
int u, v; cin >> u >> v; u--, v--;
adj[u].push_back(v); adj[v].push_back(u);
}
vector<int> suff(n, 0);
for (int i = n-2; i > -1; i--) suff[i] = max(suff[i+1], a[i]);
int cur = 0, ans = 0;
for (int i = 0; i < n-1; i++){
if (suff[i+1] < cur) cur--, ans++;
else if (cur < a[i+1]) {
int delta = a[i+1] - cur;
ans += delta; cur += delta;
} else if (cur < suff[i+1]){
cur++, ans++;
} else ans++;
} ans += cur;
cout << ans << endl;
return 0;
}
