#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int t, a, b, c, d, i, j, k, l, n, m, x, y, z;
  cin >> n;
  k = 0;
  long long int s[n + 5];
  for (i = 0; i < n; i++) cin >> s[i];
  j = 0;
  l = 0;
  x = s[0];
  j = x + 1;
  for (i = 1; i < n; i++) {
    j++;
    a = abs(x - s[i]);
    j += a;
    j++;
    x = s[i];
  }
  cout << j;
}
