#include <bits/stdc++.h>
using namespace std;
int main() {
  long long a, b, c, d = 0, e = 0, f = 0, g = 0, i, j, k = 1, l = 1, r = 1,
                     n[11], m[100001], q, u, v, w, y, z[11], h[300001],
                     p[300001];
  string s, t, x;
  cin >> a;
  for (i = 1; i <= a; i++) {
    cin >> p[i];
    if (i == 1) {
      d += p[i] + 1;
    } else {
      if (p[i] >= p[i - 1]) {
        d += p[i] - p[i - 1] + 2;
      } else {
        d += p[i - 1] - p[i] + 2;
      }
    }
  }
  cout << d;
}
