#include <bits/stdc++.h>
using namespace std;
long long oo = 1e9;
long long nmod(long long a) { return (((a % oo) + oo) % oo); }
int dx[] = {0, 0, 1, -1, -1, -1, 1, 1};
int dy[] = {1, -1, 0, 0, -1, 1, -1, 1};
int dxk[] = {1, 1, 2, 2, -1, -1, -2, -2};
int dyk[] = {2, -2, 1, -1, 2, -2, 1, -1};
int r, c;
bool val(int r1, int c1) { return (r1 > -1 && r1 < r && c1 > -1 && c1 < c); }
int ar[100001];
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &ar[i]);
  }
  int sm = 0;
  int here = 0;
  for (int i = 0; i < n; i++) {
    if (i == 0) {
      here = ar[i];
      sm += ar[i] + 1;
      continue;
    }
    if (here <= ar[i]) {
      sm += ar[i] + 2 - here;
    } else if (here > ar[i]) {
      sm += here - ar[i] + 2;
    }
    here = ar[i];
  }
  printf("%d", sm);
  return 0;
}
