#include <bits/stdc++.h>
#define int long long
using namespace std;
signed main() {
    cin.tie(0)->sync_with_stdio(0);
    int n; cin >> n;
    vector<int> A(n+1,0);
    A[1] = 1;
    for(int i=2;i<=n;i++) {
        cin >> A[i];
    }
    A[2] = 0;
    int c1 = 0;
    for(int i=3;i<=n;i++) {
        c1+=A[i];
    }
    if(n-2==c1) {
        cout << 1;
        return 0;
    }
    int ans = 0;
    while(A.size() && A.back()==0) {
        ans++;
        A.pop_back();
    }
    cout << max(2LL,ans+1);
}