#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define io ios::sync_with_stdio(0), cin.tie(0);
#define endl '\n'
#define MXN (ll)1e6+5
int main(){
    int n;
    cin >> n;
    int arr[n-1];
    int nw = 0, mx = 0, flag = 0, ans = 0, a1 = 0;
    for(int i=0;i<n-1;i++) {
        cin >> arr[i];
        if(arr[i]) {
            flag = 1;
            a1++;
            nw = 0;
        } else {
            flag = 0;
            nw++;
        }
    }
    if(a1 == n-1) {
        cout << 1 << endl;
    } else if(flag) {
        cout << 2 << endl;
    } else {
        cout << max(nw+1, 2) << endl;
    }
 }