#include <fstream>
#include <iostream>
using namespace std;

int n;
int a[1000001];
int ind;

void read() {
    int i;
    ifstream f("operatii.in");
    f >> n;
    for (i = 1; i <= n; i++)
        f >> a[i];
    f.close();
}

long long nr;

void solve(int x) {
    while (ind <= n) {
        if (a[ind] != x) 
            if (x == 0) {
                nr++;
                solve(a[ind]);
            }
            else break;
        else ind++;
    }
}   

void output() {
    ofstream g("operatii.out");
    g << nr;
    g.close();
}

int main() {
    read();
    ind = 1;
    solve(0);
    output();
    return 0;
}