// #pragma GCC optimizer("Ofast")
// #pragma GCC target("avx2")
#include <bits/stdc++.h>
#define int long long 
#define ld long double
#define ull unsigned long long 
#define fr first
#define fi first
#define sc second
#define se second
#define all(x) x.begin(), x.end()
#define pii pair<int,int>
//#define sz(x) (int)x.size()
using namespace std;

#ifndef fireball
#define tofu ios::sync_with_stdio(0); cin.tie(0);
#else
#define tofu freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
#endif 

void db() {cout << '\n';}
template <typename T, typename ...U> void db(T a, U ...b) {cout << a << ' ', db(b...);}
const int INF = 1ll << 60;
signed main(){
    tofu;
    int n; cin >> n;

    int a[n - 1];
    for(int i = 0; i < n - 1; ++i) cin >> a[i];

    int cnt = 0;
    for(int i = n - 2; i >= 0; --i){
        if(a[i] == 0) cnt++;
        else break;
    }

    int ans = 0;
    for(int i = 1; i < n - 1 - cnt; ++i) if(a[i] == 0) ans = 2;
    if(cnt == n - 1) db(cnt);
    else db(max(cnt + 1, ans));
}