#include <bits/stdc++.h>
inline int two(int n) { return 1 << n; }
inline int test(int n, int b) { return (n >> b) & 1; }
inline void set_bit(int& n, int b) { n |= two(b); }
inline void unset_bit(int& n, int b) { n &= ~two(b); }
inline int last_bit(int n) { return n & (-n); }
inline int ones(int n) {
  int res = 0;
  while (n && ++res) n -= n & (-n);
  return res;
}
long long int gcd(long long int a, long long int b) {
  return (a ? gcd(b % a, a) : b);
}
long long int modPow(long long int a, long long int b, long long int MOD) {
  long long int x = 1, y = a;
  while (b > 0) {
    if (b % 2 == 1) {
      x = (x * y) % MOD;
    }
    b /= 2;
    y = (y * y) % MOD;
  }
  return x;
}
long long int modInverse(long long int a, long long int p) {
  return modPow(a, p - 2, p);
}
using namespace std;
const int N = 1e2 + 2;
int arr[N];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, ans, i, j, k;
  cin >> n;
  ans = 0;
  int f = 0;
  int start, end;
  start = n;
  end = n - 1;
  for (int i = 0; i < (n); i++) {
    cin >> arr[i];
    if (arr[i] == 1 && f == 0) {
      f = 1;
      start = i;
    }
    if (arr[i] == 1) end = i;
  }
  for (i = start; i <= end;) {
    if (arr[i] == 0) {
      for (j = i + 1; j <= end; j++) {
        if (arr[j] == 1) break;
      }
      if (j - i == 1 && j != n) ans++;
      i = j;
    } else if (arr[i] == 1) {
      ans++;
      i++;
    }
  }
  cout << ans;
}
