#include <bits/stdc++.h>
using namespace std;
long long int n, a[100008], cnt = 0;
int main() {
  ios_base::sync_with_stdio(0);
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> a[i];
  for (int i = 1; i <= n; i++) {
    if (a[i] == 1) {
      if (!cnt) cnt++;
      int j = i + 1;
      while (a[j] != 1 && j <= n) j++;
      if (a[j] == 1) {
        cnt += min(j - i, 2);
        i = j - 1;
      }
    }
  }
  cout << cnt << endl;
}
