#include <bits/stdc++.h>
using namespace std;
const int maxn = 110;
int a[maxn];
int main() {
  int n;
  while (cin >> n) {
    int ans = 0;
    for (int i = 1; i <= n; i++) {
      cin >> a[i];
      if (a[i]) ans++;
    }
    for (int i = 1; i <= n; i++) {
      if (a[i] == 1) {
        if (i == 1) continue;
        if (a[i - 1] && i >= 1) continue;
        if (i >= 2 && a[i - 2]) {
          ans++;
          continue;
        }
      }
    }
    cout << ans << endl;
  }
}
