#include "bits/stdc++.h"
using namespace std;

typedef long long ll;
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(),(x).end()
int main()
{
    ios::sync_with_stdio(0);cin.tie(0);
    int n;
    cin>>n;
    vector a(n+1,0);
    for(int i=2;i<=n;i++)
    cin>>a[i];
    int tp=2;
    for(int i=n;i>2;i--)
    if(a[i])
    {
        tp=i;
        break;
    }
    if(tp==2)
    {
        cout<<n-1<<'\n';
        return 0;
    }
    if(tp<n)
    {
        cout<<n-tp+1<<'\n';
        return 0;
    }
    if(*min_element(a.begin()+3,a.end())==0)
    cout<<2<<'\n';
    else
    cout<<1<<'\n';
}