#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
const int maxn = 1e6 + 10;
int v[maxn];
int32_t main() {
ios_base::sync_with_stdio(false); cin.tie(0);
int n, m; cin >> n >> m;
int res = 0, height = 0;
for (int i = 0; i < n; i++) {
int cur; cin >> cur;
if(i == n - 1 || i == 0) continue;
if(cur > height) {
res += cur - height;
height += cur - height;
} else {
height--; res++;
}
}
if(height == 0) res++;
else res += height;
for (int i = 0; i < m; i++) {
int a, b; cin >> a >> b;
}
cout << res << '\n';
return 0;
}
