#include <iostream>
#include <stack>

using namespace std;

int n, res = 0;
stack<int> stk;

int main()
{
    cin >> n;
    while (n--)
    {
        int x;
        cin >> x;
        stk.push(x);
    }

    while(!stk.empty())
    {
        if (!stk.top()) res++;
        stk.pop();
    }

    cout << res << endl;

    return 0;
}